U.S. patent application number 15/319487 was filed with the patent office on 2017-06-01 for inter-layer video encoding method for compensating for luminance difference and device therefor, and video decodingmethod and device therefor.
This patent application is currently assigned to SAMSUNG ELECTRONICS CO., LTD.. The applicant listed for this patent is SAMSUNG ELECTRONICS CO., LTD.. Invention is credited to Jin-young LEE, Min-woo PARK.
Application Number | 20170155920 15/319487 |
Document ID | / |
Family ID | 54935804 |
Filed Date | 2017-06-01 |
United States Patent
Application |
20170155920 |
Kind Code |
A1 |
PARK; Min-woo ; et
al. |
June 1, 2017 |
INTER-LAYER VIDEO ENCODING METHOD FOR COMPENSATING FOR LUMINANCE
DIFFERENCE AND DEVICE THEREFOR, AND VIDEO DECODINGMETHOD AND DEVICE
THEREFOR
Abstract
Disclosed is an inter-layer video decoding method including
decoding a first layer image, determining a reference location of
the first layer image corresponding to a location of a second layer
current block, determining neighboring sample values by using
sample values of a boundary of the first layer image when
neighboring sample locations of the reference location are outside
the boundary of the first layer image, and determining an
illumination compensation parameter of the second layer current
block based on the neighboring sample values.
Inventors: |
PARK; Min-woo; (Yongin-si,
KR) ; LEE; Jin-young; (Suwon-si, KR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
SAMSUNG ELECTRONICS CO., LTD. |
Suwon-si |
|
KR |
|
|
Assignee: |
SAMSUNG ELECTRONICS CO.,
LTD.
Suwon-si
KR
|
Family ID: |
54935804 |
Appl. No.: |
15/319487 |
Filed: |
June 28, 2015 |
PCT Filed: |
June 28, 2015 |
PCT NO: |
PCT/KR2015/006215 |
371 Date: |
December 16, 2016 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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62013805 |
Jun 18, 2014 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H04N 19/503 20141101;
H04N 19/625 20141101; H04N 19/55 20141101; H04N 19/176 20141101;
H04N 19/105 20141101; H04N 19/52 20141101; H04N 19/563 20141101;
H04N 19/186 20141101; H04N 19/30 20141101 |
International
Class: |
H04N 19/52 20060101
H04N019/52; H04N 19/55 20060101 H04N019/55; H04N 19/563 20060101
H04N019/563; H04N 19/176 20060101 H04N019/176; H04N 19/625 20060101
H04N019/625 |
Claims
1. An inter-layer video decoding method comprising: decoding a
first layer image; determining a reference location of the first
layer image corresponding to a location of a second layer current
block; determining neighboring sample values by using sample values
of a boundary of the first layer image when neighboring sample
locations of the reference location are outside the boundary of the
first layer image; and determining an illumination compensation
parameter of the second layer current block based on the
neighboring sample values.
2. The method of claim 1, wherein the determining of the
neighboring sample values comprises clipping the neighboring sample
locations of the reference location based on the boundary of the
first layer image.
3. The method of claim 1, wherein the determining of the
neighboring sample values comprises: determining the neighboring
sample values by using sample values of a left boundary or a right
boundary of the first layer image when the neighboring sample
locations are outside the left boundary or the right boundary of
the first layer image; and determining the neighboring sample
values by using sample values of a top boundary or a bottom
boundary of the first layer image when the neighboring sample
locations are outside the top boundary or the bottom boundary of
the first layer image.
4. The method of claim 1, further comprising compensating an
illumination value of the second layer current block by using the
determined illumination compensation parameter.
5. The method of claim 1, wherein the determining of the reference
location of the first layer image comprises: obtaining a disparity
vector indicating a first layer reference block corresponding to
the second layer current block; and determining the reference
location of the first layer image corresponding to the location of
the second layer current block by using the disparity vector.
6. The method of claim 1, wherein the determining of the reference
location of the first layer image comprises determining the
reference location based on an integer-pel location adjacent to a
location of a first layer indicated by the disparity vector.
7. The method of claim 1, wherein a sub-pel location of the first
layer image is determined as the reference location when the
disparity vector indicates the sub-pel location, and wherein the
neighboring sample locations are determined based on the determined
reference location.
8. The method of claim 1, wherein the illumination compensation
parameter comprises at least one of a scale factor and an
offset.
9. An inter-layer video decoding apparatus comprising: a first
layer decoder configured to reconstruct a first layer image; and a
second layer decoder configured to reconstruct a second layer image
by using the reconstructed first layer image, wherein the second
layer decoder comprises: a neighboring sample determiner configured
to determine a reference location of the first layer image
corresponding to a location of a second layer current block, and
determine neighboring sample values by using sample values of a
boundary of the first layer image when neighboring sample locations
of the reference location are outside the boundary of the first
layer image; and an illumination compensation parameter determiner
configured to determine an illumination compensation parameter of
the second layer current block based on the neighboring sample
values.
10. (canceled)
11. An inter-layer video encoding method comprising: encoding a
first layer image; determining a reference location of the first
layer image corresponding to a location of a second layer current
block; determining neighboring sample values by using sample values
of a boundary of the first layer image when neighboring sample
locations of the reference location are outside the boundary of the
first layer image; and determining an illumination compensation
parameter of the second layer current block based on the
neighboring sample values.
12. The method of claim 11, wherein the determining of the
neighboring sample values comprises clipping the neighboring sample
locations of the reference location based on the boundary of the
first layer image.
13. The method of claim 11, wherein the determining of the
neighboring sample values comprises: determining the neighboring
sample values by using sample values of a left boundary or a right
boundary of the first layer image when the neighboring sample
locations are outside the left boundary or the right boundary of
the first layer image; and determining the neighboring sample
values by using sample values of a top boundary or a bottom
boundary of the first layer image when the neighboring sample
locations are outside the top boundary or the bottom boundary of
the first layer image.
14. The method of claim 1, further comprising compensating an
illumination value of the second layer current block by using the
determined illumination compensation parameter.
15. The method of claim 11, wherein the determining of the
reference location of the first layer image comprises: obtaining a
disparity vector indicating a first layer reference block
corresponding to the second layer current block; and determining
the reference location of the first layer image corresponding to
the location of the second layer current block by using the
disparity vector.
16. The method of claim 11, wherein the determining of the
reference location of the first layer image comprises determining
the reference location based on an integer-pel location adjacent to
a location of a first layer indicated by the disparity vector.
17. The method of claim 11, wherein a sub-pel location of the first
layer image is determined as the reference location when the
disparity vector indicates the sub-pel location, and wherein the
neighboring sample locations are determined based on the determined
reference location.
18. The method of claim 11, wherein the illumination compensation
parameter comprises at least one of a scale factor and an
offset.
19. (canceled)
Description
TECHNICAL FIELD
[0001] The present disclosure relates to inter-layer video encoding
methods and decoding methods, and more particularly, to methods of
inducing an illumination compensation parameter for illumination
compensation between inter-layer images.
BACKGROUND ART
[0002] As hardware for reproducing and storing high resolution or
high quality video content is being developed and supplied, a need
for a video codec for effectively encoding or decoding the high
resolution or high quality video content is increasing. According
to a conventional video codec, a video is encoded according to a
limited encoding method based on a macroblock having a
predetermined size.
[0003] Image data of a spatial domain is transformed into
coefficients of a frequency domain via frequency transformation.
According to a video codec, an image is split into blocks having a
predetermined size, discrete cosine transformation (DCT) is
performed on each block, and frequency coefficients are encoded in
block units, for rapid calculation of frequency transformation.
Compared with image data of a spatial domain, coefficients of a
frequency domain are easily compressed. In particular, since an
image pixel value of a spatial domain is expressed according to a
prediction error via inter prediction or intra prediction of a
video codec, when frequency transformation is performed on the
prediction error, a large amount of data may be transformed to 0.
According to a video codec, an amount of data may be reduced by
replacing data that is consecutively and repeatedly generated with
small-sized data.
[0004] A multilayer video codec encodes and decodes a first layer
video and at least one second layer video. Amounts of data of the
first layer video and the second layer video may be reduced by
removing temporal/spatial redundancy and layer redundancy of the
first layer video and the second layer video.
DETAILED DESCRIPTION OF THE INVENTION
Technical Problem
[0005] First layer neighboring sample locations for inducing an
illumination compensation parameter may be outside a boundary of a
first layer image of a multilayer image.
Technical Solution
[0006] Provided are an inter-layer video encoding method, an
apparatus therefor, and an inter-layer video decoding method
capable of increasing coding efficiency by using sample values of a
boundary of a first layer image of a multilayer image when first
layer neighboring sample locations used to induce an illumination
compensation parameter are outside the boundary of the first layer
image.
[0007] According to an aspect of an embodiment, an inter-layer
video decoding method includes decoding a first layer image,
determining a reference location of the first layer image
corresponding to a location of a second layer current block,
determining neighboring sample values by using sample values of a
boundary of the first layer image when neighboring sample locations
of the reference location are outside the boundary of the first
layer image, and determining an illumination compensation parameter
of the second layer current block based on the neighboring sample
values.
[0008] The technical problems of the present disclosure are not
limited to the aforementioned features, and other unstated
technical problems will be clearly understood by one of ordinary
skill in the art in view of descriptions below.
DESCRIPTION OF THE DRAWINGS
[0009] FIG. 1A is a block diagram of an inter-layer video encoding
apparatus according to various embodiments.
[0010] FIG. 1B is a flowchart of an inter-layer video encoding
method according to various embodiments.
[0011] FIG. 2A is a block diagram of an inter-layer video decoding
apparatus according to various embodiments.
[0012] FIG. 2B is a flowchart of an inter-layer video decoding
method according to various embodiments.
[0013] FIG. 3 illustrates an inter-layer prediction structure
according to an embodiment.
[0014] FIG. 4 illustrates an example of a method of determining an
illumination compensation parameter, according to an
embodiment.
[0015] FIGS. 5A and 5B illustrate an example of a process of
determining neighboring sample locations of a first layer image,
according to various embodiments.
[0016] FIGS. 6A to 6C illustrate examples of a method of
determining a reference location to determine first layer
neighboring sample values, according to various embodiments.
[0017] FIGS. 7A to 7C illustrate examples of a method of
determining a reference location to determine first layer
neighboring sample values, according to various embodiments.
[0018] FIG. 8 is a block diagram of a video encoding apparatus
based on coding units according to a tree structure, according to
an embodiment.
[0019] FIG. 9 is a block diagram of a video decoding apparatus
based on coding units according to a tree structure, according to
an embodiment.
[0020] FIG. 10 is a diagram for describing a concept of coding
units, according to an embodiment of the present disclosure.
[0021] FIG. 11 is a block diagram of an image encoder based on
coding units, according to an embodiment of the present
disclosure.
[0022] FIG. 12 is a block diagram of an image decoder based on
coding units, according to an embodiment of the present
disclosure.
[0023] FIG. 13 is a diagram illustrating coding units and
partitions, according to an embodiment of the present
disclosure.
[0024] FIG. 14 is a diagram for describing a relationship between a
coding unit and transformation units, according to an embodiment of
the present disclosure.
[0025] FIG. 15 is a diagram illustrating a plurality of pieces of
encoding information, according to an embodiment of the present
disclosure.
[0026] FIG. 16 is a diagram of coding units, according to an
embodiment of the present disclosure.
[0027] FIGS. 17, 18, and 19 are diagrams for describing a
relationship between coding units, prediction units, and
transformation units, according to an embodiment of the present
disclosure.
[0028] FIG. 20 is a diagram for describing a relationship between a
coding unit, a prediction unit, and a transformation unit,
according to encoding mode information of Table 1.
[0029] FIG. 21 is a diagram of a physical structure of a disc in
which a program is stored, according to an embodiment.
[0030] FIG. 22 is a diagram of a disc drive for recording and
reading a program by using the disc.
[0031] FIG. 23 is a diagram of an overall structure of a content
supply system for providing a content distribution service.
[0032] FIGS. 24 and 25 are diagrams respectively of an external
structure and an internal structure of a mobile phone to which the
video encoding method and video decoding method of the present
disclosure are applied, according to an embodiment.
[0033] FIG. 26 is a diagram of a digital broadcast system to which
a communication system according to the present disclosure is
applied.
[0034] FIG. 27 is a diagram illustrating a network structure of a
cloud computing system that uses the video encoding apparatus and
video decoding apparatus according to the present disclosure of the
present disclosure.
BEST MODE
[0035] According to an aspect of an embodiment, an inter-layer
video decoding method includes decoding a first layer image,
determining a reference location of the first layer image
corresponding to a location of a second layer current block,
determining neighboring sample values by using sample values of a
boundary of the first layer image when neighboring sample locations
of the reference location are outside the boundary of the first
layer image, and determining an illumination compensation parameter
of the second layer current block based on the neighboring sample
values.
[0036] The determining of the neighboring sample values may include
clipping the neighboring sample locations of the reference location
based on the boundary of the first layer image.
[0037] The determining of the neighboring sample values may include
determining the neighboring sample values by using sample values of
a left boundary or a right boundary of the first layer image when
the neighboring sample locations are outside the left boundary or
the right boundary of the first layer image, and determining the
neighboring sample values by using sample values of a top boundary
or a bottom boundary of the first layer image when the neighboring
sample locations are outside the top boundary or the bottom
boundary of the first layer image.
[0038] The method may further include compensating an illumination
value of the second layer current block by using the determined
illumination compensation parameter.
[0039] The determining of the reference location of the first layer
image may include obtaining a disparity vector indicating a first
layer reference block corresponding to the second layer current
block, and determining the reference location of the first layer
image corresponding to the location of the second layer current
block by using the disparity vector.
[0040] The determining of the reference location of the first layer
image may include determining the reference location based on an
integer-pel location adjacent to a location of a first layer
indicated by the disparity vector.
[0041] A sub-pel location of the first layer image may be
determined as the reference location when the disparity vector
indicates the sub-pel location, and the neighboring sample
locations may be determined based on the determined reference
location.
[0042] The illumination compensation parameter may include at least
one of a scale factor and an offset.
[0043] According to an aspect of another embodiment, an inter-layer
video decoding apparatus includes a first layer decoder configured
to reconstruct a first layer image, and a second layer decoder
configured to reconstruct a second layer image by using the
reconstructed first layer image, wherein the second layer decoder
includes a neighboring sample determiner configured to determine a
reference location of the first layer image corresponding to a
location of a second layer current block, and determine neighboring
sample values by using sample values of a boundary of the first
layer image when neighboring sample locations of the reference
location are outside the boundary of the first layer image, and an
illumination compensation parameter determiner configured to
determine an illumination compensation parameter of the second
layer current block based on the neighboring sample values.
[0044] According to an aspect of another embodiment, an inter-layer
video encoding method includes encoding a first layer image,
determining a reference location of the first layer image
corresponding to a location of a second layer current block,
determining neighboring sample values by using sample values of a
boundary of the first layer image when neighboring sample locations
of the reference location are outside the boundary of the first
layer image, and determining an illumination compensation parameter
of the second layer current block based on the neighboring sample
values.
[0045] The determining of the neighboring sample values may include
clipping the neighboring sample locations of the reference location
based on the boundary of the first layer image.
[0046] The determining of the neighboring sample values may include
determining the neighboring sample values by using sample values of
a left boundary or a right boundary of the first layer image when
the neighboring sample locations are outside the left boundary or
the right boundary of the first layer image, and determining the
neighboring sample values by using sample values of a top boundary
or a bottom boundary of the first layer image when the neighboring
sample locations are outside the top boundary or the bottom
boundary of the first layer image.
[0047] The method may further include compensating an illumination
value of the second layer current block by using the determined
illumination compensation parameter.
[0048] The determining of the reference location of the first layer
image may include obtaining a disparity vector indicating a first
layer reference block corresponding to the second layer current
block, and determining the reference location of the first layer
image corresponding to the location of the second layer current
block by using the disparity vector.
[0049] The determining of the reference location of the first layer
image may include determining the reference location based on an
integer-pel location adjacent to a location of a first layer
indicated by the disparity vector.
[0050] A sub-pel location of the first layer image may be
determined as the reference location when the disparity vector
indicates the sub-pel location, and the neighboring sample
locations may be determined based on the determined reference
location.
[0051] The illumination compensation parameter may include at least
one of a scale factor and an offset.
[0052] According to an aspect of another embodiment, an inter-layer
video encoding apparatus includes a first layer encoder configured
to encode a first layer image, and a second layer encoder
configured to encode a second layer image by using the first layer
image, wherein the second layer encoder includes a neighboring
sample determiner configured to determine a reference location of
the first layer image corresponding to a location of a second layer
current block, and determine neighboring sample values by using
sample values of a boundary of the first layer image when
neighboring sample locations of the reference location are outside
the boundary of the first layer image, and an illumination
compensation parameter determiner configured to determine an
illumination compensation parameter of the second layer current
block based on the neighboring sample values.
Mode of the Invention
[0053] Hereinafter, with reference to FIGS. 1A to 7C, an
inter-layer video encoding technique and an inter-layer video
decoding technique for determining whether to perform illumination
compensation, based on block characteristics, according to various
embodiments will be described. Also, with reference to FIGS. 8
through 20, a video encoding technique and a video decoding
technique, which are based on coding units having a tree structure,
according to embodiments that are applicable to the inter-layer
video encoding and decoding techniques will be described. Also,
with reference to FIGS. 21 through 27, various embodiments to which
the video encoding method and the video decoding method are
applicable will be described.
[0054] Hereinafter, an `image` may refer to a still image or a
moving image of a video, or a video itself.
[0055] Hereinafter, a `sample` refers to data that is assigned to a
sampling location of an image and is to be processed. For example,
pixel values of an image or residuals of a block in the spatial
domain may be samples.
[0056] Initially, with reference to FIGS. 1 A to 7C, an inter-layer
video encoding apparatus, an inter-layer video encoding method, an
inter-layer video decoding apparatus, and an inter-layer video
decoding method according to embodiments will be described.
[0057] FIG. 1A is a block diagram of an inter-layer video encoding
apparatus 10 according to various embodiments.
[0058] The inter-layer video encoding apparatus 10 according to
various embodiments includes a first layer encoder 12 and a second
layer encoder 14. The second layer encoder 14 may include a
neighboring sample determiner 16 and an illumination compensation
parameter determiner 18. Alternatively, the second layer encoder 14
may further include an illumination compensation determiner (not
shown) for determining whether to perform illumination compensation
on a second layer current block.
[0059] The neighboring sample determiner 16 and the illumination
compensation parameter determiner 18 according to another
embodiment may be located outside the second layer encoder 14.
[0060] The inter-layer video encoding apparatus 10 according to
various embodiments may classify a plurality of image sequences
according to layers, may encode each of the image sequences
according to a scalable video coding scheme, and may output
separate streams including data encoded according to layers. The
inter-layer video encoding apparatus 10 may encode a first layer
image sequence and a second layer image sequence in different
layers.
[0061] The first layer encoder 12 may encode first layer images and
output a first layer stream including the encoded data of the first
layer images.
[0062] The second layer encoder 14 may encode second layer images
and output a second layer stream including the encoded data of the
second layer images.
[0063] For example, according to a scalable video coding scheme
based on spatial scalability, low resolution images may be encoded
as first layer images, and high resolution images may be encoded as
second layer images. An encoding result of the first layer images
may be output as a first layer stream, and an encoding result of
the second layer images may be output as a second layer stream.
[0064] As another example, a multiview video may be encoded
according to a scalable video coding scheme. Left-view images may
be encoded as first layer images and right-view images may be
encoded as second layer images. Alternatively, central-view images,
left-view images, and right-view images may be each encoded,
wherein the central-view images are encoded as first layer images,
the left-view images are encoded as second layer images, and the
right-view images are encoded as third layer images. Alternatively,
a central-view texture image, a central-view depth image, a
left-view texture image, a left-view depth image, a right-view
texture image, and a right-view depth image may be respectively
encoded as a first layer image, a second layer image, a third layer
image, a fourth layer image, a fifth layer image, and a sixth layer
image. As another example, a central-view texture image, a
central-view depth image, a left-view depth image, a left-view
texture image, a right-view depth image, and a right-view texture
image may be respectively encoded as a first layer image, a second
layer image, a third layer image, a fourth layer image, a fifth
layer image, and a sixth layer image.
[0065] As another example, a scalable video coding method may be
performed according to temporal hierarchical prediction based on
temporal scalability. A first layer stream including encoding
information generated by encoding base frame rate images may be
output. Temporal levels may be classified according to frame rates
and each temporal level may be encoded according to layers. A
second layer stream including encoding information of a high frame
rate may be output by further encoding higher frame rate images by
referring to the base frame rate images.
[0066] Alternatively, scalable video coding may be performed on a
first layer and a plurality of extension layers (e.g., a second
layer, a third layer, . . . , and a K-th layer). When the number of
extension layers is three or more, first layer images and second to
K-th layer images may be encoded. As such, a result of encoding the
first layer images may be output as a first layer stream, and
results of encoding the second to K-th layer images may be output
as second to K-th layer streams, respectively.
[0067] The inter-layer video encoding apparatus 10 according to
various embodiments may perform inter prediction to predict a
current image with reference to images of a single layer. Due to
inter prediction, a motion vector indicating motion information
between a current image and a reference image, and residuals
between the current image and the reference image may be
generated.
[0068] In addition, the inter-layer video encoding apparatus 10 may
perform inter-layer prediction to predict second layer images with
reference to first layer images.
[0069] Alternatively, when the inter-layer video encoding apparatus
10 according to an embodiment allows three or more layers, e.g., a
first layer, a second layer, and a third layer, the inter-layer
video encoding apparatus 10 may perform inter-layer prediction
between a first layer image and a third layer image and between a
second layer image and a third layer image based on a multilayer
prediction structure.
[0070] By performing inter-layer prediction, a displacement
component between the current image and a reference image of a
different layer, and a residual component between the current image
and the reference image of the different layer may be
generated.
[0071] An inter-layer prediction structure will be described below
with reference to FIG. 3.
[0072] The inter-layer video encoding apparatus 10 according to
various embodiments may perform encoding based on blocks of each
image of a video, according to layers. A block may have a square
shape, a rectangular shape, or an arbitrary geometrical shape, and
is not limited to a data unit having a predetermined size. The
block may be a maximum coding unit, a coding unit, a prediction
unit, or a transformation unit, among coding units according to a
tree structure. A largest coding unit including coding units of a
tree structure may be called differently, such as a coding tree
unit, a coding block tree, a block tree, a root block tree, a
coding tree, a coding root, or a tree trunk. Video encoding and
decoding methods based on coding units according to a tree
structure will be described below with reference to FIGS. 8 through
20.
[0073] Inter prediction and inter-layer prediction may be performed
based on a data unit, such as a coding unit, a prediction unit, or
a transformation unit.
[0074] The first layer encoder 12 according to various embodiments
may generate symbol data by performing source coding operations
including inter prediction or intra prediction on first layer
images. Symbol data indicates a sample value of each encoding
parameter and a sample value of a residual.
[0075] For example, the first layer encoder 12 may generate symbol
data by performing inter or intra prediction, transformation, and
quantization on samples of a data unit of first layer images, and
may generate a first layer stream by performing entropy encoding on
the symbol data.
[0076] The second layer encoder 14 may encode second layer images
based on coding units of a tree structure. The second layer encoder
14 may generate symbol data by performing inter/intra prediction,
transformation, and quantization on samples of a coding unit of
second layer images, and generate a second layer stream by
performing entropy encoding on the symbol data.
[0077] The second layer encoder 14 according to various embodiments
may perform inter-layer prediction to predict a second layer image
by using reconstructed samples of a first layer image. To encode an
original second layer image of a second layer image sequence based
on an inter-layer prediction structure, the second layer encoder 14
may generate a predicted second layer image by using a
reconstructed first layer image, and encode a prediction error
between an original second layer image and the predicted second
layer image.
[0078] The second layer encoder 14 may perform inter-layer
prediction on the second layer image per block, e.g., per coding
unit or prediction unit. A block of the reconstructed first layer
image to be referred by a block of the second layer image may be
determined. For example, a reference block of the first layer image
provided at a location corresponding to the location of a current
block of the second layer image may be determined. The second layer
encoder 14 may determine a second layer prediction block by using
the first layer reference block corresponding to the second layer
block.
[0079] The second layer encoder 14 may use the second layer
prediction block determined by using the first layer reference
block according to an inter-layer prediction structure, as a
reference image for inter-layer prediction with respect to a second
layer original block. The second layer encoder 14 may perform
entropy encoding by transforming and quantizing an error, i.e., a
residual component according to inter-layer prediction, between a
sample value of a second layer prediction block and a sample value
of a second layer original block, by using a reconstructed first
layer image.
[0080] As described above, the second layer encoder 14 may encode a
current layer image sequence with reference to the first layer
images reconstructed based on the inter-layer prediction structure.
Alternatively, the second layer encoder 14 according to various
embodiments may encode the second layer image sequence based on a
single layer prediction structure without reference to samples of
another layer. Accordingly, it should be noted that the second
layer encoder 14 does not always perform inter-layer prediction to
encode the second layer image sequence.
[0081] As described above, when the inter-layer video encoding
apparatus 10 encodes a multiview video, the first layer encoder 12
may encode a first view video and the second layer encoder 14 may
encode a second view video. The different view videos may be
obtained by using different cameras or different lenses. Since
different views may have different characteristics of shooting
angles, lighting levels, or imaging devices (e.g., cameras or
lenses), an illumination mismatch may occur between the videos
obtained in different views. This illumination mismatch phenomenon
may be related to the difference of sample values between the
different view videos.
[0082] When an illumination mismatch occurs between the different
view videos, an inter-layer prediction error may be increased and
thus coding efficiency may be lowered. As such, in consideration of
an illumination mismatch between views, the second layer encoder 14
of the inter-layer video encoding apparatus 10 may compensate for
and encode an illumination difference between different view
videos. For example, an illumination difference between the first
view image to be encoded by the first layer encoder 12 and the
second view image to be encoded by the second layer encoder 14 may
be encoded. Since the illumination difference between the first
view image and the second view image is encoded, illumination
compensation may be performed when the second layer encoder 14
encodes the second view video.
[0083] The inter-layer video encoding apparatus 10 may determine
whether to perform illumination compensation, in consideration of
characteristics per predetermined data unit such as a slice or
block of a current image, e.g., partition type information of a
current block. The inter-layer video encoding apparatus 10 may
generate a second layer bitstream including a parameter indicating
whether to perform illumination compensation.
[0084] According to various embodiments, an illumination
compensation parameter may be used for illumination compensation
between a first layer block and a second layer block. For example,
the illumination compensation parameter may include at least one of
a scale factor and an offset.
[0085] The illumination compensation parameter including the scale
factor and the offset for illumination compensation between block
units may be transmitted in a bitstream or induced by using
neighboring sample values of a second layer current block and
neighboring sample values of a first layer reference block
corresponding to the current block.
[0086] Specifically, the neighboring sample determiner 16 of the
second layer encoder 14 may determine a reference location of the
first layer image, and determine the neighboring sample values of
the first layer reference block based on the reference location. A
disparity vector indicating a view difference between layers may be
used to determine the first layer reference block corresponding to
the second layer current block. The disparity vector may be
transmitted in a bitstream or induced from other types of coding
information.
[0087] The disparity vector may indicate the reference location of
the first layer image corresponding to the location of the second
layer current block. The location of the second layer current block
may be the location of a top-left corner sample of the current
block as a base location. The reference location of the first layer
image may be the location of a top-left corner sample of the first
layer reference block.
[0088] The neighboring sample determiner 16 may determine
neighboring sample locations based on the reference location. For
example, the neighboring sample locations may include top sample
locations and left sample locations adjacent to the first layer
reference block and determined based on the reference location. The
neighboring sample locations are locations for determining the
neighboring sample values used to induce the illumination
compensation parameter, and may be locations spaced apart from the
reference location by a predetermined offset.
[0089] The illumination compensation parameter determiner 18 of the
second layer encoder 14 may determine the neighboring sample values
based on whether the neighboring sample locations are valid, and
determine the illumination compensation parameter of the second
layer current block based on the determined neighboring sample
values. The fact that the neighboring sample locations are valid
may mean that the neighboring sample locations are provided within
the first layer image. A method of determining the illumination
compensation parameter will be described in detail below with
reference to FIG. 4.
[0090] In this case, when the neighboring sample locations of the
reference block are outside a boundary of the first layer image, no
neighboring sample values of the reference block may be present.
Thus, coding efficiency may be reduced. In addition, the amount of
calculation for coding may be increased to determine whether the
neighboring sample locations are valid.
[0091] Accordingly, when the neighboring sample locations based on
the first layer reference location are outside the boundary of the
first layer image, the inter-layer video encoding apparatus 10
according to various embodiments may change the neighboring sample
locations based on boundary locations of the first layer image and
determine the illumination compensation parameter of the second
layer current block by using sample values of the boundary of the
first layer image.
[0092] By using the sample values of the boundary of the first
layer image, the inter-layer video encoding apparatus 10 does not
need to check validity of the neighboring sample values and may
obtain more accurate sample values, thereby increasing coding
efficiency. For example, the inter-layer video encoding apparatus
10 may not check validity of the neighboring sample values of the
first layer and may perform illumination compensation based on
whether neighboring sample values of the second layer current block
are valid.
[0093] Operation of the inter-layer video encoding apparatus 10 for
determining the illumination compensation parameter will now be
described in detail with reference to FIG. 1B.
[0094] FIG. 1B is a flowchart of an inter-layer video encoding
method according to various embodiments.
[0095] In operation 11, the inter-layer video encoding apparatus 10
may encode a first layer image and output a first layer bitstream
including the encoded data.
[0096] In operation 13, the inter-layer video encoding apparatus 10
may determine a reference location of the first layer image
corresponding to the location of a second layer current block.
[0097] The inter-layer video encoding apparatus 10 may obtain and
use a disparity vector of the second layer current block indicating
a first layer reference block. The disparity vector may be induced
from neighboring blocks of the current block. Otherwise, the
disparity vector may be induced from a depth map block
corresponding thereto. Alternatively, the disparity vector may be
obtained from a bitstream.
[0098] The inter-layer video encoding apparatus 10 may determine
the reference location of the first layer image corresponding to
the location of the second layer current block, by using the
disparity vector. The reference location of the first layer image
may be the location of a top-left sample of the first layer
reference block corresponding to the second layer current
block.
[0099] Since the disparity vector may have fractional pixel
accuracy, e.g., quarter-pel or half-pel accuracy, the location of
the first layer image indicated by the disparity vector of the
second layer current block may be a sub-pel location. The sub-pel
location may be a pixel location other than an integer-pel
location.
[0100] When the disparity vector indicates a sub-pel location, the
inter-layer video encoding apparatus 10 may determine an
integer-pel location adjacent to the sub-pel location as the
reference location to reduce complexity of calculation.
Alternatively, when the disparity vector indicates a sub-pel
location, the inter-layer video encoding apparatus 10 may determine
the sub-pel location as the reference location to improve accuracy
of an illumination compensation parameter and thus to increase
coding efficiency. A process of determining the reference location
will be described in detail below with reference to FIGS. 6A to
7B.
[0101] The inter-layer video encoding apparatus 10 may determine
the first layer reference block based on the determined reference
location. For example, the reference location may be the location
of a top-left corner of the first layer reference block.
[0102] In operation 15, when neighboring sample locations of the
reference location are outside a boundary of the first layer image,
the inter-layer video encoding apparatus 10 may determine
neighboring sample values by using sample values of the boundary of
the first layer image.
[0103] Specifically, the inter-layer video encoding apparatus 10
may determine the first layer neighboring sample locations based on
the reference location. For example, the neighboring sample
locations may be determined as locations spaced apart from the
reference location by a predetermined offset.
[0104] The inter-layer video encoding apparatus 10 may determine
whether the determined neighboring sample locations are outside the
boundary of the first layer image. For example, the inter-layer
video encoding apparatus 10 may determine whether the neighboring
sample locations are outside the boundary of the first layer image,
by comparing the neighboring sample locations to boundary locations
of the first layer image. The inter-layer video encoding apparatus
10 may compare first component values of the neighboring sample
locations to a left boundary and a right boundary of the first
layer image, and compare second component values of the neighboring
sample locations to a top boundary and a bottom boundary of the
first layer image. The first component values may be x component
values, and the second component values may be y component
values.
[0105] When the neighboring sample locations are outside the
boundary of the first layer image, the inter-layer video encoding
apparatus 10 may determine the neighboring sample values by using
the sample values of the boundary of the first layer image. For
example, the inter-layer video encoding apparatus 10 may change the
neighboring sample locations based on the boundary locations of the
first layer image, and the neighboring sample values may be the
sample values of the boundary of the first layer image.
[0106] For example, the inter-layer video encoding apparatus 10 may
determine the neighboring sample values by clipping the neighboring
sample locations based on the boundary of the first layer image.
For example, when the first component values of the neighboring
sample locations are outside the left boundary or the right
boundary of the first layer image, the inter-layer video encoding
apparatus 10 may change the neighboring sample values into sample
values of the left boundary or the right boundary of the first
layer image. Alternatively, when the second component values of the
neighboring sample locations are outside the top boundary or the
bottom boundary of the first layer image, the inter-layer video
encoding apparatus 10 may change the neighboring sample values into
sample values of the top boundary or the bottom boundary of the
first layer image. The first component values may be horizontal
component values, and the second component values may be vertical
component values.
[0107] Alternatively, the inter-layer video encoding apparatus 10
may determine the neighboring sample values by padding the
neighboring sample values of the reference location by using the
sample values of the boundary of the first layer image.
[0108] The inter-layer video encoding apparatus 10 may determine a
first layer illumination compensation sample list including the
determined neighboring sample values.
[0109] In operation 17, the inter-layer video encoding apparatus 10
may determine an illumination compensation parameter of the second
layer current block based on the determined neighboring sample
values. The illumination compensation parameter may include at
least one of a scale factor and an offset.
[0110] The inter-layer video encoding apparatus 10 may determine
the illumination compensation parameter by comparing the determined
neighboring sample values of the first layer reference block to
neighboring sample values of the second layer current block. For
example, the inter-layer video encoding apparatus 10 may determine
the illumination compensation parameter by comparing the first
layer illumination compensation sample list to a second layer
illumination compensation sample list. A method of determining the
illumination compensation parameter will be described in detail
below with reference to FIG. 4.
[0111] The inter-layer video encoding apparatus 10 may generate a
second layer bitstream including information indicating whether to
perform illumination compensation, and inter-layer prediction
information between the first layer reference block and the second
layer current block, an illumination value of which is compensated
based on the illumination compensation parameter.
[0112] The inter-layer video encoding apparatus 10 may encode and
transmit information indicating whether to perform illumination
compensation on the current block, and the disparity vector used to
determine the illumination compensation parameter, in a bitstream.
When the information indicating whether to perform illumination
compensation, and the disparity vector used to determine the
illumination compensation parameter may be determined based on
pre-encoded information, the inter-layer video encoding apparatus
10 may not transmit the information indicating whether to perform
illumination compensation, and the disparity vector.
[0113] Alternatively, the inter-layer video encoding apparatus 10
may encode and transmit the information indicating whether to
perform illumination compensation, in a bitstream, and may encode
and transmit the disparity vector used to determine the
illumination compensation parameter, in a bitstream, or may not
transmit the disparity vector when the disparity vector may be
determined based on pre-encoded information.
[0114] By compensating an illumination difference between the first
layer image and a second layer image, an error between the second
layer image and the first layer image may be reduced and thus
coding efficiency of inter-layer prediction may be improved.
[0115] The inter-layer video encoding apparatus 10 according to
various embodiments may include a central processor (not shown) for
controlling all of the first layer encoder 12, the second layer
encoder 14, the neighboring sample determiner 16, and the
illumination compensation parameter determiner 18. Alternatively,
the first layer encoder 12, the second layer encoder 14, the
neighboring sample determiner 16, and the illumination compensation
parameter determiner 18 may be controlled by individual processors
(not shown) and the processors may operate in association with each
other to control the inter-layer video encoding apparatus 10.
Otherwise, the first layer encoder 12, the second layer encoder 14,
the neighboring sample determiner 16, and the illumination
compensation parameter determiner 18 may be controlled by an
external processor (not shown) of the inter-layer video encoding
apparatus 10.
[0116] The inter-layer video encoding apparatus 10 may include one
or more data storages (not shown) for storing input and output data
of the first layer encoder 12, the second layer encoder 14, the
neighboring sample determiner 16, and the illumination compensation
parameter determiner 18. The inter-layer video encoding apparatus
10 may include a memory controller (not shown) for controlling data
input and output of the data storages.
[0117] In order to output a video encoding result, the inter-layer
video encoding apparatus 10 may operate in cooperation with an
internal video encoding processor installed therein or an external
video encoding processor so as to perform video encoding operations
including transformation. The internal video encoding processor of
the inter-layer video encoding apparatus 10 may perform the video
encoding operations as a separate processor. Also, basic video
encoding operations may be realized as the inter-layer video
encoding apparatus 10, a central processing apparatus, or a graphic
processing apparatus includes a video encoding processing
module.
[0118] FIG. 2A is a block diagram of an inter-layer video decoding
apparatus 20 according to various embodiments.
[0119] The inter-layer video decoding apparatus 20 according to
various embodiments includes a first layer decoder 22 and a second
layer decoder 24. The second layer decoder 24 may include a
neighboring sample determiner 26 and an illumination compensation
parameter determiner 28. Alternatively, the second layer decoder 24
may further include an illumination compensation determiner (not
shown) for determining whether to perform illumination compensation
on a second layer current block.
[0120] The neighboring sample determiner 26 and the illumination
compensation parameter determiner 28 according to another
embodiment may be located outside the second layer decoder 24.
[0121] The inter-layer video decoding apparatus 20 according to
various embodiments may receive bitstreams according to layers, via
a scalable encoding scheme. The number of layers of bitstreams
received by the inter-layer video decoding apparatus 20 is not
limited. However, for convenience of description, an embodiment in
which the first layer decoder 22 of the inter-layer video decoding
apparatus 20 receives and decodes a first layer stream and the
second layer decoder 24 receives and decodes a second layer stream
will be described.
[0122] For example, the inter-layer video decoding apparatus 20
based on spatial scalability may receive a stream in which image
sequences having different resolutions are encoded in different
layers. A first layer stream may be decoded to reconstruct an image
sequence having low resolution and a second layer stream may be
decoded to reconstruct an image sequence having high
resolution.
[0123] As another example, a multiview video may be decoded
according to a scalable video coding scheme. When a stereoscopic
video stream is received in a plurality of layers, a first layer
stream may be decoded to reconstruct left-view images. A second
layer stream in addition to the first layer stream may be further
decoded to reconstruct right-view images.
[0124] Alternatively, when a multiview video stream is received in
a plurality of layers, a first layer stream may be decoded to
reconstruct central-view images. A second layer stream in addition
to the first layer stream may be further decoded to reconstruct
left-view images. A third layer stream in addition to the first
layer stream may be further decoded to reconstruct right-view
images.
[0125] As another example, a scalable video coding method based on
temporal scalability may be performed. A first layer stream may be
decoded to reconstruct base frame rate images. A second layer
stream may be further decoded to reconstruct high frame rate
images.
[0126] Also, when there are at least three second layers, first
layer images may be reconstructed from a first layer stream, and
when a second layer stream is further decoded by referring to
reconstructed first layer images, second layer images may be
further reconstructed. When K-th layer stream is further decoded by
referring to reconstructed second layer images, K-th layer images
may be further reconstructed.
[0127] The inter-layer video decoding apparatus 20 may obtain
encoded data of first layer images and second layer images from a
first layer stream and a second layer stream, and in addition, may
further obtain a motion vector generated via inter prediction and
prediction information generated via inter-layer prediction.
[0128] For example, the inter-layer video decoding apparatus 20 may
decode inter-predicted data per layer, and may decode inter-layer
predicted data between a plurality of layers. Reconstruction may be
performed through motion compensation and inter-layer decoding
based on a coding unit or a prediction unit.
[0129] Images may be reconstructed by performing motion
compensation for a current image by referencing reconstructed
images predicted via inter prediction of a same layer, with respect
to each layer stream. Motion compensation is an operation in which
a reconstructed image of a current image is reconstructed by
synthesizing a reference image determined by using a motion vector
of the current image and a residual component of the current
image.
[0130] In addition, the inter-layer video decoding apparatus 20 may
perform inter-layer decoding with reference to the first layer
images to reconstruct the inter-layer predicted second layer
images. The inter-layer decoding refers to an operation of
configuring a reconstructed image of a current image by combining
an another-layer reference image determined to predict the current
image, and residuals of the current image.
[0131] The inter-layer video decoding apparatus 20 according to an
embodiment may perform inter-layer decoding for reconstructing
third layer images predicted by referring to second layer images.
An inter-layer prediction structure will be described below with
reference to FIG. 3.
[0132] However, the second layer decoder 24 according to various
embodiments may decode a second layer stream without having to
reference a first layer image sequence. Accordingly, it should not
be limitedly construed that the second layer decoder 24 performs
inter-layer prediction to decode a second layer image sequence.
[0133] The inter-layer video decoding apparatus 20 performs
decoding according to blocks of each image of a video. A block may
be, from among coding units according to a tree structure, a
largest coding unit, a coding unit, a prediction unit, or a
transformation unit.
[0134] The first layer decoder 22 may decode a first layer image by
using parsed encoding symbols of the first layer image. When the
inter-layer video decoding apparatus 20 receives streams encoded
based on coding units of a tree structure, the first layer decoder
22 may perform decoding based on the coding units of the tree
structure, according to a largest coding unit of a first layer
stream.
[0135] The first layer decoder 22 may obtain decoding information
and decoded data by performing entropy decoding per largest coding
unit. The first layer decoder 22 may reconstruct a residual
component by performing inverse quantization and inverse
transformation on encoded data obtained from a stream. The first
layer decoder 22 according to another embodiment may directly
receive a bitstream of quantized transformation coefficients. The
residual component of images may be reconstructed by performing
inverse quantization and inverse transformation on quantized
transformation coefficients.
[0136] The first layer decoder 22 may reconstruct first layer
images by combining the prediction image and the residual component
via motion compensation between same layer images.
[0137] According to an inter-layer prediction structure, the second
layer decoder 24 may generate a second layer prediction image by
using samples of a reconstructed first layer image. The second
layer decoder 24 may obtain a prediction error according to
inter-layer prediction by decoding a second layer stream. The
second layer decoder 24 may generate a reconstructed second layer
image by combining a second layer prediction image and the
prediction error.
[0138] The second layer decoder 24 may determine a second layer
prediction image by using a first layer reference image decoded by
the first layer decoder 22. According to an inter-layer prediction
structure, the second layer decoder 24 may determine a block of a
first layer image which is to be referenced by a block such as a
coding unit or a prediction unit of a second layer image. For
example, a reference block of the first layer image provided at a
location corresponding to the location of a current block of the
second layer image may be determined. The second layer decoder 24
may determine a second layer prediction block by using the first
layer reference block corresponding to the second layer block.
[0139] The second layer decoder 24 may use the second layer
prediction block determined by using the first layer reference
block based on an inter-layer prediction structure, as a reference
image for inter-layer prediction on a second layer original block.
In this case, the second layer decoder 24 may reconstruct the
second layer block by combining sample values of the second layer
prediction block determined by using the reconstructed first layer
image, and residuals based on inter-layer prediction.
[0140] Based on spatial scalable video coding, when the first layer
decoder 22 has reconstructed the first layer image having a
resolution different from that of the second layer image, the
second layer decoder 24 may interpolate the first layer reference
image to adjust the resolution thereof to be the same as the
resolution of the original second layer image. The interpolated
first layer reference image may be determined as a predicted second
layer image for inter-layer prediction.
[0141] Accordingly, the first layer decoder 22 of the inter-layer
video decoding apparatus 20 may reconstruct a first layer image
sequence by decoding a first layer stream, and the second layer
decoder 24 may reconstruct a second layer image sequence by
decoding a second layer stream.
[0142] In consideration of an illumination mismatch between views,
the illumination compensation parameter determiner 28 of the
inter-layer video decoding apparatus 20 may compensate for and
reconstruct an illumination difference between different view
videos. For example, an illumination difference between the first
view image to be decoded by the first layer decoder 22 and the
second view image to be encoded by the second layer decoder 24 may
be obtained from a bitstream. Since the illumination difference
between the first view image and the second view image is obtained,
whether to perform illumination compensation may be determined when
the second layer decoder 24 decodes the second view video.
[0143] The inter-layer video decoding apparatus 20 according to
various embodiments may use an illumination compensation parameter
for illumination compensation between a first layer block and a
second layer block. For example, the illumination compensation
parameter may include at least one of a scale factor and an
offset.
[0144] The inter-layer video decoding apparatus 20 may receive
information indicating whether to perform illumination
compensation, from the bitstream, and determine whether to perform
illumination compensation on the second layer current block.
Alternatively, the inter-layer video decoding apparatus 20 may
determine whether to perform illumination compensation, in
consideration of other types of coding information, e.g., partition
type information of a current block.
[0145] Specifically, the neighboring sample determiner 26 of the
second layer decoder 24 may determine a reference location of the
first layer image, and determine neighboring sample values of the
first layer reference block based on the reference location. A
disparity vector indicating a view difference between layers may be
used to determine the first layer reference block corresponding to
the second layer current block. The disparity vector may be
transmitted in a bitstream or induced from other types of coding
information.
[0146] The disparity vector may indicate the reference location of
the first layer image corresponding to the location of the second
layer current block. The location of the second layer current block
may be the location of a top-left corner sample of the current
block as a base location. The reference location of the first layer
image may be the location of a top-left corner sample of the first
layer reference block.
[0147] The neighboring sample determiner 26 may determine
neighboring sample locations based on the reference location. For
example, the neighboring sample locations may include top sample
locations and left sample locations adjacent to the first layer
reference block and determined based on the reference location.
Specifically, the neighboring sample locations may be locations
spaced apart from the reference location by a predetermined
offset.
[0148] The illumination compensation parameter determiner 28 of the
second layer decoder 24 may determine the neighboring sample values
based on whether the neighboring sample locations are valid, and
determine the illumination compensation parameter of the second
layer current block based on the determined neighboring sample
values. The fact that the neighboring sample locations are valid
may mean that the neighboring sample locations are provided within
the first layer image. A method of determining the illumination
compensation parameter will be described in detail below with
reference to FIG. 4.
[0149] In this case, when the neighboring sample locations of the
reference block are outside a boundary of the first layer image, no
neighboring sample values of the reference block may be present.
Thus, coding efficiency may be reduced. In addition, the amount of
calculation for coding may be increased to determine whether the
neighboring sample locations are valid.
[0150] Accordingly, when the neighboring sample locations based on
the first layer reference location is outside the boundary of the
first layer image, the inter-layer video decoding apparatus 20
according to an embodiment may change the neighboring sample
locations based on boundary locations of the first layer image and
determine the illumination compensation parameter of the second
layer current block by using sample values of the boundary of the
first layer image.
[0151] By using the sample values of the boundary of the first
layer image, the inter-layer video decoding apparatus 20 does not
need to check validity of the neighboring sample values and may
obtain more accurate sample values, thereby increasing coding
efficiency. For example, the inter-layer video decoding apparatus
20 may not check validity of the neighboring sample values of the
first layer and may perform illumination compensation based on
whether neighboring sample values of the second layer current block
are valid.
[0152] Operation of the inter-layer video decoding apparatus 20 for
determining the illumination compensation parameter will now be
described in detail with reference to FIG. 2B.
[0153] FIG. 2B is a flowchart of an inter-layer video decoding
method according to various embodiments.
[0154] In operation 21, the inter-layer video decoding apparatus 20
may decode a first layer image. The inter-layer video decoding
apparatus 20 may receive a first layer bitstream and decode the
first layer image.
[0155] In operation 23, the inter-layer video decoding apparatus 20
may determine a reference location of the first layer image
corresponding to the location of a second layer current block.
[0156] The inter-layer video decoding apparatus 20 may obtain and
use a disparity vector of the second layer current block indicating
a first layer reference block. The disparity vector may be induced
from neighboring blocks of the current block. Alternatively, the
disparity vector may be obtained from a bitstream.
[0157] The inter-layer video decoding apparatus 20 may determine
the reference location of the first layer image corresponding to
the location of the second layer current block, by using the
disparity vector. The reference location of the first layer image
may be the location of a top-left sample of the first layer
reference block corresponding to the second layer current
block.
[0158] Since the disparity vector may have fractional pixel
accuracy, e.g., quarter-pel or half-pel accuracy, the location of
the first layer image indicated by the disparity vector of the
second layer current block may be a sub-pel location. The sub-pel
location may be a pixel location other than an integer-pel
location.
[0159] When the disparity vector indicates a sub-pel location, the
inter-layer video decoding apparatus 20 may determine an
integer-pel location adjacent to the sub-pel location as the
reference location to reduce complexity of calculation.
Alternatively, when the disparity vector indicates a sub-pel
location, the inter-layer video decoding apparatus 20 may determine
the sub-pel location as the reference location to improve accuracy
of an illumination compensation parameter and thus to increase
coding efficiency. A process of determining the reference location
will be described in detail below with reference to FIGS. 6A to
7B.
[0160] The inter-layer video decoding apparatus 20 may determine
the first layer reference block based on the determined reference
location. For example, the reference location may be the location
of a top-left corner of the first layer reference block.
[0161] In operation 25, when neighboring sample locations of the
reference location are outside a boundary of the first layer image,
the inter-layer video decoding apparatus 20 may determine
neighboring sample values by using sample values of the boundary of
the first layer image.
[0162] Specifically, the inter-layer video decoding apparatus 20
may determine the first layer neighboring sample locations based on
the reference location. For example, the neighboring sample
locations may be determined as locations spaced apart from the
reference location by a predetermined offset.
[0163] The inter-layer video decoding apparatus 20 may determine
whether the determined neighboring sample locations are outside the
boundary of the first layer image. For example, the inter-layer
video decoding apparatus 20 may determine whether the neighboring
sample locations are outside the boundary of the first layer image,
by comparing the neighboring sample locations to boundary locations
of the first layer image. The inter-layer video decoding apparatus
20 may compare first component values of the neighboring sample
locations to a left boundary and a right boundary of the first
layer image, and compare second component values of the neighboring
sample locations to a top boundary and a bottom boundary of the
first layer image. The first component values may be x component
values, and the second component values may be y component
values.
[0164] When the neighboring sample locations are outside the
boundary of the first layer image, the inter-layer video decoding
apparatus 20 may determine the neighboring sample values by using
the sample values of the boundary of the first layer image. For
example, the inter-layer video decoding apparatus 20 may change the
neighboring sample locations based on the boundary locations of the
first layer image, and the neighboring sample values may be the
sample values of the boundary of the first layer image.
[0165] For example, the inter-layer video decoding apparatus 20 may
determine the neighboring sample values by clipping the neighboring
sample locations based on the boundary of the first layer image.
For example, when the first component values of the neighboring
sample locations are outside the left boundary or the right
boundary of the first layer image, the inter-layer video decoding
apparatus 20 may change the neighboring sample values into sample
values of the left boundary or the right boundary of the first
layer image. Alternatively, when the second component values of the
neighboring sample locations are outside the top boundary or the
bottom boundary of the first layer image, the inter-layer video
decoding apparatus 20 may change the neighboring sample values into
sample values of the top boundary or the bottom boundary of the
first layer image. The first component values may be horizontal
component values, and the second component values may be vertical
component values.
[0166] Alternatively, the inter-layer video decoding apparatus 20
may determine the neighboring sample values by padding the
neighboring sample values of the reference location by using the
sample values of the boundary of the first layer image.
[0167] The inter-layer video decoding apparatus 20 may determine a
first layer illumination compensation sample list including the
determined neighboring sample values.
[0168] In operation 27, the inter-layer video decoding apparatus 20
may determine an illumination compensation parameter of the second
layer current block based on the determined neighboring sample
values. The illumination compensation parameter may include at
least one of a scale factor and an offset.
[0169] The inter-layer video decoding apparatus 20 may determine
the illumination compensation parameter by comparing the determined
neighboring sample values of the first layer reference block to
neighboring sample values of the second layer current block. For
example, the inter-layer video decoding apparatus 20 may determine
the illumination compensation parameter by comparing the first
layer illumination compensation sample list to a second layer
illumination compensation sample list. A method of determining the
illumination compensation parameter will be described in detail
below with reference to FIG. 4.
[0170] As described above, the inter-layer video decoding apparatus
20 may decode the second layer block on which illumination
compensation, an illumination value of which is compensated based
on the determined illumination compensation parameter.
[0171] The inter-layer video decoding apparatus 20 according to
various embodiments may include a central processor (not shown) for
controlling all of the first layer decoder 22, the second layer
decoder 24, the neighboring sample determiner 26, and the
illumination compensation parameter determiner 28. Alternatively,
the first layer decoder 22, the second layer decoder 24, the
neighboring sample determiner 26, and the illumination compensation
parameter determiner 28 may be controlled by individual processors
(not shown) and the processors may operate in association with each
other to control the inter-layer video decoding apparatus 20.
Otherwise, the first layer decoder 22, the second layer decoder 24,
the neighboring sample determiner 26, and the illumination
compensation parameter determiner 28 may be controlled by an
external processor (not shown) of the inter-layer video decoding
apparatus 20.
[0172] The inter-layer video decoding apparatus 20 may include one
or more data storages (not shown) for storing input and output data
of the first layer decoder 22, the second layer decoder 24, the
neighboring sample determiner 26, and the illumination compensation
parameter determiner 28. The inter-layer video decoding apparatus
20 may include a memory controller (not shown) for controlling data
input and output of the data storages.
[0173] In order to decode and reconstruct a video, the inter-layer
video decoding apparatus 20 may operate in cooperation with an
internal video decoding processor installed therein or an external
video decoding processor so as to perform video decoding operations
including inverse transformation. The internal video decoding
processor of the inter-layer video decoding apparatus 20 may
include an individual processor or a video decoding module included
in the inter-layer video decoding apparatus 20, a central
processing unit, or a graphics processing unit to perform basic
video decoding operations.
[0174] Referring to FIGS. 2A and 2B, since the inter-layer video
decoding apparatus 20 compensates for an illumination difference
between different layer images or different views per a certain
type of block or slice to decode a second layer image, a
reconstructed first layer image and a reconstructed second layer
image may have uniform illumination values. Referring to FIGS. 1A
and 1B, since the inter-layer video encoding apparatus 10
compensates for an illumination difference between different layer
images per a certain type of block or slice, residuals between a
predicted image and an original image may be reduced. Accordingly,
coding efficiency may be increased.
[0175] In addition, coding efficiency may be further increased by
more accurately determining first layer neighboring sample values
used to induce an illumination compensation parameter, based on a
boundary of the first layer image.
[0176] FIG. 3 illustrates an inter-layer prediction structure
according to an embodiment.
[0177] The inter-layer video encoding apparatus 10 according to an
embodiment may prediction-encode base-view images, left-view
images, and right-view images based on a reproduction order 30 of a
multiview video prediction structure.
[0178] According to the reproduction order 30 of the multiview
video prediction structure according to a related technology,
images of the same view are arranged in a horizontal direction.
Accordingly, the left-view images indicated by `Left` are arranged
in the horizontal direction in a row, the base view images
indicated by `Center` are arranged in the horizontal direction in a
row, and the right-view images indicated by `Right` are arranged in
the horizontal direction in a row. Compared to the left/right-view
images, the base view images may be central-view images.
[0179] Also, images having the same picture order count (POC) order
are arranged in a vertical direction. A POC order of images
indicates a reproduction order of images forming a video. `POC X`
indicated in the reproduction order 30 of the multiview video
prediction structure indicates a relative reproduction order of
images in a corresponding column, wherein a reproduction order is
in front when a value of X is low, and is behind when the value of
X is high.
[0180] Thus, according to the reproduction order 30 of the
multiview video prediction structure according to the related
technology, the left-view images indicated by `Left` are arranged
in the horizontal direction according to the POC order
(reproduction order), the base view images indicated by `Center`
are arranged in the horizontal direction according to the POC order
(reproduction order), and the right-view images indicated by
`Right` are arranged in the horizontal direction according to the
POC order (reproduction order). Also, the left-view image and the
right-view image located on the same column as the base view image
have different views but the same POC order (reproduction
order).
[0181] Four consecutive images form one group of pictures (GOP)
according to views. Each GOP includes images between consecutive
anchor pictures, and one anchor picture (key picture).
[0182] An anchor picture is a random access point, and when a
reproduction location is arbitrarily selected from images arranged
according to a reproduction order, i.e., a POC order, while
reproducing a video, an anchor picture closest to the reproduction
location according to the POC order is reproduced. The base layer
images include base layer anchor pictures 31, 32, 33, 34, and 35,
the left-view images include left-view anchor pictures 131, 132,
133, 134, and 135, and the right-view images include right-view
anchor pictures 231, 232, 233, 234, and 235.
[0183] Multiview images may be reproduced and predicted
(reconstructed) according to a GOP order. First, according to the
reproduction order 30 of the multiview video prediction structure,
images included in GOP 0 may be reproduced, and then images
included in GOP 1 may be reproduced, according to views. That is,
images included in each GOP may be reproduced in an order of GOP 0,
GOP 1, GOP 2, and GOP 3. Also, according to a coding order of the
multiview video prediction structure, the images included in GOP 0
may be predicted (reconstructed), and then the images included in
GOP 1 may be predicted (reconstructed), according to views. That
is, the images included in each GOP may be predicted
(reconstructed) in an order of GOP 0, GOP 1, GOP 2, and GOP 3.
[0184] According to the reproduction order 30 of the multiview
video prediction structure, inter-view prediction (inter-layer
prediction) and inter prediction are performed on images. In the
multiview video prediction structure, an image where an arrow
starts is a reference image, and an image where an arrow ends is an
image predicted by using a reference image.
[0185] A prediction result of base view images may be encoded and
then output in a form of a base view image stream, and a prediction
result of additional view images may be encoded and then output in
a form of a layer bitstream. Also, a prediction encoding result of
left-view images may be output as a first layer bitstream, and a
prediction encoding result of right-view images may be output as a
second layer bitstream.
[0186] Only inter-prediction is performed on base view images. That
is, the base layer anchor pictures 31, 32, 33, 34, and 35 of an
I-picture type do not refer to other images, but remaining images
of B- and b-picture types are predicted by referring to other base
view images. Images of a B-picture type are predicted by referring
to an anchor picture of an I-picture type, which precedes the
images of a B-picture type according to a POC order, and a
following anchor picture of an I-picture type. Images of a
b-picture type are predicted by referring to an anchor picture of
an I-type, which precedes the image of a b-picture type according a
POC order, and a following image of a B-picture type, or by
referring to an image of a B-picture type, which precedes the
images of a b-picture type according to a POC order, and a
following anchor picture of an I-picture type.
[0187] Inter-view prediction (inter-layer prediction) that
references different view images, and inter prediction that
references same view images are performed on each of left-view
images and right-view images.
[0188] Inter-view prediction (inter-layer prediction) may be
performed on the left-view anchor pictures 131, 132, 133, 134, and
135 by respectively referring to the base view anchor pictures 31,
32, 33, 34, and 35 having the same POC order. Inter-view prediction
may be performed on the right-view anchor pictures 231, 232, 233,
234, and 235 by respectively referring to the base view anchor
pictures 31, 32, 33, 34, and 35 or the left-view anchor pictures
131, 132, 133, 134, and 135 having the same POC order. Also,
inter-view prediction (inter-layer prediction) may be performed on
remaining images other than the left-view images 131, 132, 133,
134, and 135 and the right-view images 231, 232, 233, 234, and 235
by referring to other view images having the same POC.
[0189] Remaining images other than the anchor pictures 131, 132,
133, 134, 135, 231, 232, 233, 234, and 235 from among left-view
images and right-view images are predicted by referring to the same
view images.
[0190] However, each of the left-view images and the right-view
images may not be predicted by referring to an anchor picture that
has a preceding reproduction order from among additional view
images of the same view. In other words, in order to perform inter
prediction on a current left-view image, left-view images excluding
a left-view anchor picture that precedes the current left-view
image in a reproduction order may be referenced. Equally, in order
to perform inter prediction on a current right-view image,
right-view images excluding a right-view anchor picture that
precedes the current right-view image in a reproduction order may
be referenced.
[0191] Also, in order to perform inter prediction on a current
left-view image, prediction may be performed by referring to a
left-view image that belongs to a current GOP but is to be
reconstructed before the current left-view image, instead of
referring to a left-view image that belongs to a GOP before the
current GOP of the current left-view image. The same is applied to
a right-view image.
[0192] The inter-layer video decoding apparatus 20 according to an
embodiment may reconstruct base view images, left-view images, and
right-view images according to the reproduction order 30 of the
multiview video prediction structure of FIG. 3.
[0193] Left-view images may be reconstructed via inter-view
disparity compensation that references base view images and
inter-image motion compensation that references left-view images.
Right-view images may be reconstructed via inter-view disparity
compensation that references base view images and left-view images,
and inter-image motion compensation that references right-view
images. Reference images may be reconstructed first for disparity
compensation and motion compensation of left-view images and
right-view images.
[0194] For inter-image motion compensation of a left-view image,
left-view images may be reconstructed via inter-image motion
compensation that references a reconstructed left-view reference
image. For inter-image motion compensation of a right-view image,
right-view images may be reconstructed via inter-image motion
compensation that references a reconstructed right-view reference
image.
[0195] Also, for inter-image motion compensation of a current
left-view image, only a left-view image that belongs to a current
GOP of the current left-view image but is to be reconstructed
before the current left-view image may be referenced, and a
left-view image that belongs to a GOP before the current GOP is not
referenced. The same is applied to a right-view image.
[0196] As described above, the inter-layer video encoding apparatus
10 and the inter-layer video decoding apparatus 20 may determine
whether to perform illumination compensation, based on image
characteristics. For example, whether to perform illumination
compensation on a block may be determined based on a coding mode of
the block, a prediction direction of the block, and a coding type,
which are determined based on rate-distortion (RD)
optimization.
[0197] FIG. 4 illustrates an example of a method of determining an
illumination compensation parameter, according to an
embodiment.
[0198] The inter-layer video decoding apparatus 20 according to an
embodiment may obtain information indicating whether to perform
illumination compensation per coding unit, and determine the
illumination compensation parameter for each color component (e.g.,
Y, U, or V) of each prediction direction per prediction unit of
each coding unit. In this case, the illumination compensation
parameter may be determined based on neighboring samples of a
current block and neighboring samples of a reference block of
another layer corresponding to the current block. That is, the
illumination compensation parameter may be determined by comparing
neighboring samples of the reference block of a first layer to
neighboring samples of the current block of a second layer. The
illumination compensation parameter may include at least one of a
scale factor a and an offset b.
[0199] In this case, the neighboring samples of the current block
used to induce the illumination compensation parameter may refer to
usable neighboring samples of the current block, which are already
reconstructed before the current block is reconstructed.
Accordingly, when the neighboring samples of the current block are
not usable, the illumination compensation parameter may not be
induced. That is, the inter-layer video decoding apparatus 20 may
determine whether to perform illumination compensation, based on
whether the neighboring sample values of the current block are
usable.
[0200] To determine the illumination compensation parameter, a
first layer reference block 45 corresponding to a second layer
current block 40 should be found. In this case, a disparity vector
may be used. Herein, the disparity vector is a vector indicating a
location difference between the second layer current block 40 and
the first layer reference block 45.
[0201] For example, FIG. 4 shows the second layer current block 40
configured as an 8.times.8 block and the first layer reference
block 45 corresponding to the second layer current block 40. The
inter-layer video decoding apparatus 20 may determine a reference
location 46 of a first layer image indicated by the disparity
vector, based on a location 41 of the second layer current block
40. The location 41 of the current block is a base location of the
current block 40 and may be the location of a top-left corner
thereof, and the reference location 46 may be the location of a
top-left corner of the first layer reference block 45 corresponding
to the second layer current block 40.
[0202] When the first layer reference block 45 is determined, the
illumination compensation parameter may be determined by using
neighboring samples 42 of the second layer current block 40 and
neighboring samples 47 of the first layer reference block 45. The
illumination compensation parameter may be determined by using all
or a part of the neighboring samples 42 and 47. For example, an
average illumination difference between the neighboring samples 42
and the neighboring samples 47 may be determined as an offset, and
thus illumination compensation may be performed on the current
block 40 by the determined offset.
[0203] According to an embodiment, considering that an illumination
difference between samples within the second layer current block 40
and samples within the reference block 45 is similar to an
illumination difference between the neighboring samples 42 of the
current block 40 and the neighboring samples 47 of the reference
block 45, the inter-layer video decoding apparatus 20 may determine
the illumination compensation parameters a and b by using the
neighboring samples 42 and 47. That is, the inter-layer video
decoding apparatus 20 may determine the illumination compensation
parameter based on a first layer illumination compensation sample
list including the neighboring samples 47 of the first layer
reference block 45 and a second layer illumination compensation
sample list including the neighboring samples 42 of the second
layer current block 40.
[0204] Since a and b may be determined by using the neighboring
samples 42 and 47, even when the illumination compensation
parameter is not received as syntax, the inter-layer video decoding
apparatus 20 may calculate the illumination compensation parameter.
Accordingly, data to be transmitted may be reduced.
[0205] A method of calculating the illumination compensation
parameter includes a linear regression scheme, an average of
difference based prediction (ADP) scheme, and a difference of
average based prediction (DAP) scheme, etc. When the linear
regression scheme is used, the illumination compensation parameters
a and b may be calculated by using Equation 1.
a = N i = 0 N - 1 NB curr ( i ) NB ref ( i ) - i = 0 N - 1 NB curr
( i ) i = 0 N - 1 NB ref ( i ) N i = 0 N - 1 NB ref ( i ) NB ref (
i ) - ( i = 0 N - 1 NB ref ( i ) ) 2 b = i = 0 N - 1 NB curr ( i )
- a i = 0 N - 1 NB ref ( i ) N Equation 1 ##EQU00001##
[0206] N may be the number of neighboring samples of a block (N is
16 in FIG. 4), NB.sub.curr may be the value of the neighboring
samples 42 of the current block 40, and NB.sub.ref may be the value
of the neighboring samples 47 of the reference block 45.
[0207] The inter-layer video decoding apparatus 20 may perform
illumination compensation on the second layer current block 40 by
using the determined illumination compensation parameter. For
example, the inter-layer video decoding apparatus 20 may compensate
for an illumination value Pred(x, y) of each sample of the current
block 40 by using an illumination compensation model defined by
Equation 2.
Pred'(x, y)=a.times.Pred(x, y)+b Equation 2
[0208] As described above, since residuals between layers are
predicted in an inter-layer prediction structure, a coding
operation for predicting an illumination difference between layers
may increase the amount of calculation. In particular, an operation
of multiplying an illumination value of each pixel by the scale
factor a requires many clocks of a computer and thus load may be
generated when illumination compensation is performed.
[0209] Accordingly, the inter-layer video decoding apparatus 20
according to an embodiment may perform illumination compensation by
merely adding an offset in consideration of characteristics per
predetermined data unit such as a slice or block of a current
image. That is, illumination compensation using only an offset may
be performed by using an illumination compensation model defined by
Equation 3.
Pred'(x, y)=Pred(x, y)+b' Equation 3
[0210] The inter-layer video decoding apparatus 20 may determine
only the offset b'. The inter-layer video decoding apparatus 20 may
determine a value obtained by adding the offset b' to the
illumination value Pred(x, y) of each sample of the second layer
current block 40, as an illumination value Pred'(x, y) of each
sample of the illumination-compensated second layer current block
40. Since the illumination compensation model defined by Equation 3
does not include a multiplying operation but includes only an
offset-adding operation, the amount of calculation required for
illumination compensation may be reduced.
[0211] Although the inter-layer video decoding apparatus 20
determines the illumination compensation model and the illumination
compensation parameter in FIG. 4, it will be understood by one of
ordinary skill in the art that the method described above in
relation to FIG. 4 is also applicable to the inter-layer video
encoding apparatus 10.
[0212] FIGS. 5A and 5B illustrate an example of a process of
determining neighboring sample locations of a first layer image 50,
according to various embodiments.
[0213] To determine an illumination compensation parameter, the
inter-layer video decoding apparatus 20 according to various
embodiments may determine a first layer reference block 51
corresponding to a current block 53 of a second layer image 52 by
using a disparity vector DV. The disparity vector DV may be
transmitted in a bitstream or induced from other types of coding
information.
[0214] Referring to FIG. 5A, when neighboring sample locations 54
and 55 of the reference block 51 are outside a boundary of the
first layer image 50, no neighboring sample values of the reference
block 51 may be present. Thus, coding efficiency may be reduced. In
addition, the amount of calculation for coding may be increased to
check validity of the neighboring sample locations 54 and 55.
[0215] Accordingly, when the neighboring sample locations 54 and 55
based on a first layer reference location are outside the boundary
of the first layer image 50, the inter-layer video decoding
apparatus 20 according to various embodiments may determine
neighboring sample values by using sample values of the boundary of
the first layer image 50. For example, the neighboring sample
values may be the sample values of the boundary of the first layer
image 50.
[0216] By using the sample values of the boundary of the first
layer image 50, the inter-layer video decoding apparatus 20 does
not need to check validity of the neighboring sample values and may
obtain more accurate sample values, thereby increasing coding
efficiency. For example, the inter-layer video decoding apparatus
20 may not check validity of the neighboring sample values of the
first layer and may perform illumination compensation based on
whether neighboring sample values of the second layer current block
53 are valid.
[0217] Referring to FIG. 5B, a process of determining the
neighboring sample values by the inter-layer video decoding
apparatus 20 is shown.
[0218] When the neighboring sample locations 54 and 55 based on the
first layer reference location are outside the boundary of the
first layer image 50, the inter-layer video decoding apparatus 20
according to various embodiments may determine the neighboring
sample values by using the sample values of the boundary of the
first layer image 50.
[0219] In FIG. 5B, when the first layer neighboring sample
locations 54 and 55 are outside the boundary of the first layer
image 50, the inter-layer video decoding apparatus 20 may determine
the neighboring sample values by changing the neighboring sample
locations 54 and 55 based on boundary locations 56 and 57 of the
first layer image 50. That is, the inter-layer video decoding
apparatus 20 may determine the neighboring sample values by
clipping the neighboring sample locations 54 and 55 of the
reference location based on the boundary of the first layer image
50.
[0220] Specifically, the inter-layer video decoding apparatus 20
may compare first component values of the neighboring sample
locations 54 and 55 to a left boundary and a right boundary of the
first layer image 50, and compare second component values of the
neighboring sample locations 54 and 55 to a top boundary and a
bottom boundary of the first layer image 50. The first component
values may be x component values, and the second component values
may be y component values.
[0221] When the neighboring sample locations 54 and 55 are outside
the left boundary or the right boundary of the first layer image
50, the inter-layer video decoding apparatus 20 may determine the
neighboring sample values by using sample values of the left
boundary or the right boundary of the first layer image 50. When
the neighboring sample locations 54 and 55 are outside the top
boundary or the bottom boundary of the first layer image 50, the
inter-layer video decoding apparatus 20 may determine the
neighboring sample values by using sample values of the top
boundary or the bottom boundary of the first layer image 50.
[0222] For example, in FIG. 5B, since the neighboring sample
locations 54 are outside the left boundary of the first layer image
50, the inter-layer video decoding apparatus 20 may determine top
neighboring sample values of the first layer reference block 51 by
using a sample value of a left boundary location 56 of the first
layer image 50. In addition, since the neighboring sample locations
55 are outside the left boundary of the first layer image 50, the
inter-layer video decoding apparatus 20 may determine left
neighboring sample values of the first layer reference block 51 by
using sample values of left boundary locations 57 of the first
layer image 50. The top neighboring sample values of the first
layer reference block 51 may correspond to the sample value of the
left boundary location 56 of the first layer image 50, and the left
neighboring sample values of the first layer reference block 51 may
be the sample values of the left boundary locations 57 of the first
layer image 50.
[0223] Similarly, when the neighboring sample locations 54 and 55
are outside the right boundary of the first layer image 50, the
inter-layer video decoding apparatus 20 may determine the
neighboring sample values by using sample values of the right
boundary.
[0224] In addition, when the neighboring sample locations 54 and 55
are outside the top or bottom boundary of the first layer image 50,
the inter-layer video decoding apparatus 20 may determine the
neighboring sample values by using sample values of the top or
bottom boundary.
[0225] Specifically, when the first component values of the
neighboring sample locations 54 and 55 are outside the left
boundary or the right boundary of the first layer image 50, the
inter-layer video decoding apparatus 20 may change the first
component values of the neighboring sample locations 54 and 55
based on left or right boundary locations of the first layer image
50. When the second component values of the neighboring sample
locations 54 and 55 are outside the top boundary or the bottom
boundary of the first layer image 50, the inter-layer video
decoding apparatus 20 may change the second component values of the
neighboring sample locations 54 and 55 based on top or bottom
boundary locations of the first layer image 50. The neighboring
sample values may be sample values of the left or right boundary
locations of the first layer image 50, or sample values of the top
or bottom boundary locations of the first layer image 50.
[0226] A method of determining the first layer neighboring sample
values as described above in relation to FIG. 5B may be expressed
as the following pseudo-code.
xOff=curNbColFlag ? -1: i
yOff=curNbColFlag ? i: -1
xP=Clip3(0, (pic_width_in_luma_samples/subWidth)-1,
xRefBlkLX+xOff)
yP=Clip3(0, (pic_height_in_luma_samples/subHeight)-1,
yRefBlkLX+yOff)
refSampleListLX[numSamples]=refRecSamplesLX[xP][yP]
curSampleList[numSamples++]=curRecSamples[xC+xOff][yC+yOff]
[0227] Herein, curNbColFlag may be information indicating whether
neighboring sample locations are top neighboring sample locations
or left neighboring sample locations of a first layer reference
location. In addition, availFlagCurLeftCol and availFlagCurAboveRow
may be information indicating whether left sample values of a
second layer current block are valid, and information indicating
whether top sample values of the second layer current block are
valid, respectively. Furthermore, xRefBlkLX and yRefBlkLX may
indicate an x component and a y component of the first layer
reference location, respectively. Besides, xRefBlkLX+xOff and
yRefBlkLX+yOff may indicate x components and y components of the
neighboring sample locations based on the first layer reference
location, respectively.
[0228] The x components (xRefBlkLX+xOff) of the neighboring sample
locations may be clipped based on a left boundary location (0) of a
first layer image, which is the minimum value, and a right boundary
location ((pic_width_in_luma_samples/subWidth)-1) of the first
layer image, which is the maximum value, and changed into new x
components (xP) of the neighboring sample locations. The y
components (yRefBlkLX+yOff) of the neighboring sample locations may
be clipped based on a top boundary location (0) of the first layer
image, which is the minimum value, and a bottom boundary location
((pic_height_in_luma_samples/subHeight)-1) of the first layer
image, which is the maximum value, and changed into new y
components (yP) of the neighboring sample locations.
[0229] Herein, refRecSamplesLX[xP][yP] may indicate neighboring
sample values of a reconstructed first layer image. The inter-layer
video decoding apparatus 20 may determine a first layer
illumination compensation sample list (refSampleListLX) including
the neighboring sample values of the first layer image. In
addition, the inter-layer video decoding apparatus 20 may determine
a second layer illumination compensation sample list
(curSampleList) including neighboring sample values of a second
layer image.
[0230] Alternatively, the inter-layer video decoding apparatus 20
may determine the neighboring sample values by padding the
neighboring sample values of the reference location by using the
sample values of a boundary of the first layer image.
[0231] Since the inter-layer video decoding apparatus 20 determines
the illumination compensation parameter by using the determined
neighboring sample values of the first layer reference block 51,
more accurate neighboring sample values may be predicted and thus
coding efficiency may be increased.
[0232] Although the inter-layer video decoding apparatus 20
determines the first layer neighboring sample values used to induce
the illumination compensation parameter in FIGS. 5A and 5B, it will
be understood by one of ordinary skill in the art that the method
described above in relation to FIGS. 5A and 5B is also applicable
to the inter-layer video encoding apparatus 10.
[0233] FIGS. 6A to 6C illustrate examples of a method of
determining a reference location to determine first layer
neighboring sample values, according to various embodiments.
[0234] The inter-layer video decoding apparatus 20 according to
various embodiments may use a disparity vector indicating a view
difference between layers, to determine a first layer reference
block corresponding to a second layer current block. The disparity
vector may be transmitted in a bitstream or induced from other
types of coding information.
[0235] Since the disparity vector may have fractional pixel
accuracy, e.g., quarter-pel or half-pel accuracy, the location of a
first layer image indicated by the disparity vector of the second
layer current block may be a sub-pel location. The sub-pel location
may be a pixel location other than an integer-pel location.
[0236] When the disparity vector indicates a sub-pel location, an
integer-pel location adjacent to the sub-pel location may be the
reference location of the first layer image to reduce complexity of
calculation.
[0237] For example, FIGS. 6A to 6C illustrate examples of
determining a neighboring integer-pel indicated by the disparity
vector, according to embodiments.
[0238] In FIGS. 6A to 6C, uppercase A, B, C, and D indicate
integer-pel locations, and lowercase a to o indicate sub-pel
locations.
[0239] Referring to FIG. 6A, the inter-layer video decoding
apparatus 20 according to an embodiment may determine an
integer-pel location of a 1.times.1 block including the location of
the first layer image indicated by the disparity vector at a base
location of the second layer current block, as the first layer
reference location.
[0240] For example, when the disparity vector indicates a sub-pel
location a, b, c, d, e, f, g, h, i, j, k, l, m, n, or o of a
top-left region 60, the first layer reference location may be an
integer-pel location A.
[0241] A method of determining the reference location by using the
location of the first layer image indicated by the disparity vector
at the base location of the current block as described above in
relation to FIG. 6A may be expressed as the following
pseudo-code.
xRLX=xC+(mvLX[0]>>(2+(cldx ? 1: 0)))
yRLX=yC+(mvLX[1].times..times.(2+(cldx ? 1: 0)))
[0242] In the above pseudo-code, mvLX[0] and mvLX[1] may denote an
x component and a y component of the disparity vector, (xC, yC) may
denote a location coordinate of the current block, and cldx may
denote a Y component or a depth map when the value thereof is 0,
denote a U component when the value thereof is 1, and denote a V
component when the value thereof is 2. A luma block and a chroma
block have different sizes and thus may have different distances
between integer-pixels. Thus, when the disparity vector indicates a
sub-pixel, the method of determining the reference location may
differ based on whether a conditional "cldx? 1: 0" indicates a luma
block or a chroma block.
[0243] Accordingly, a reference block location (xRLX, yRLX)
corresponding to the current block location (xC, yC) may be
obtained based on a predetermined shift operation shown by then
above pseudo-code. Herein, each of the current block location (xC,
yC) and the reference block location (xRLX, yRLX) may be a
coordinate value of a top-left corner of the block. However, each
of the current block location (xC, yC) and the reference block
location (xRLX, yRLX) is not limited thereto and may be a
coordinate value of a center pixel of the block.
[0244] As another example, referring to FIG. 6B, the inter-layer
video decoding apparatus 20 according to an embodiment may
determine the first layer reference location by using the closest
integer-pel location to the location of the first layer image
indicated by the disparity vector at the base location of the
current block. The first layer reference location may be the
closest integer-pel location to the location of the first layer
image indicated by the disparity vector.
[0245] For example, when the disparity vector indicates a sub-pel
location a, d, or e of a top-left region 61, an integer-pel
location A may be the first layer reference location.
[0246] Likewise, when the disparity vector indicates a sub-pel
location b, c, f, or g of a top-right region 62, an integer-pel
location B may be the reference location. When the disparity vector
indicates a sub-pel location l, m, or n of a bottom-left region 63,
an integer-pel location C may be the reference location. When the
disparity vector indicates a sub-pel location j, k, n, or o of a
bottom-right region 64, an integer-pel location D may be the
reference location. Alternatively, when the disparity vector
indicates an integer-pel location, the integer-pel location may be
determined as the first layer reference location.
[0247] A method of determining the first layer reference location
by using the location indicated by the disparity vector at a base
pixel 41 of the current block as described above in relation to
FIG. 6B may be expressed as the following pseudo-code.
xRLX=xC+((mvLX[0]+(cldx ? 4: 2))>>(2+(cldx ? 1: 0)))
yRLX=yC+((mvLX[1]+(cldx ? 4: 2))>>(2+(cldx ? 1: 0)))
[0248] The above pseudo-code may be modified as shown below.
xRLX=xC+((mvLX[0]+2+(cldx ? 2: 0))>>(2+(cldx ? 1: 0)))
yRLX=yC+((mvLX[1]+2+(cldx ? 2: 0))>>(2+(cldx ? 1: 0)))
[0249] As another example, referring to FIG. 6C, when the disparity
vector indicates a sub-pel location a, b, d, e, f, h, i, or j of a
top-left region 65, the inter-layer video decoding apparatus 20
according to an embodiment may determine the first layer reference
location by using an integer-pel location A.
[0250] Likewise, when the disparity vector indicates a sub-pel
location c, g, or k of a top-right region 66, an integer-pel
location B may be determined as the reference location. When the
disparity vector indicates a sub-pel location l, m, or n of a
bottom-left region 67, an integer-pel location C may be determined
as the reference location. When the disparity vector indicates a
sub-pel location o of a bottom-right region 68, an integer-pel
location D may be determined as the reference location.
[0251] An integer-pel location determined when the disparity vector
indicates a predetermined sub-pixel is not limited to the methods
of FIGS. 6A to 6C and may be determined by using various
methods.
[0252] The inter-layer video decoding apparatus 20 may determine
neighboring sample locations of the first layer reference block
based on the determined first layer reference location, determine
neighboring sample values based on the neighboring sample
locations, and determine a first layer illumination compensation
sample list including the neighboring sample values.
[0253] Although the inter-layer video decoding apparatus 20
determines the first layer reference location in FIGS. 6A to 6C, it
will be understood by one of ordinary skill in the art that the
methods described above in relation to FIGS. 6A to 6C are also
applicable to the inter-layer video encoding apparatus 10.
[0254] FIGS. 7A to 7C illustrate examples of a method of
determining a reference location to determine first layer
neighboring sample values, according to various embodiments.
[0255] FIG. 7A illustrates a process of determining first layer
neighboring sample locations in integer-pel units, according to an
embodiment, and FIG. 7B illustrates a process of determining first
layer neighboring sample locations in sub-pixel units, according to
another embodiment.
[0256] In FIG. 7A, when a disparity vector indicates a sub-pel
location, the inter-layer video encoding apparatus 10 may determine
the first layer reference location by using an integer-pel location
adjacent to the sub-pel location, to reduce complexity of
calculation. That is, the first layer reference location may be the
location of an integer-pixel adjacent to a sub-pixel indicated by
the disparity vector.
[0257] Referring to FIG. 7A, a reference block 71 of a first layer
image is shown. The reference block 71 may be a 4.times.4 block.
The inter-layer video decoding apparatus 20 may determine a block
having a top-left corner location corresponding to a location
indicated by the disparity vector of a second layer current block,
as the reference block 71.
[0258] In this case, the inter-layer video decoding apparatus 20
may determine an integer-pel location based on the location
indicated by the disparity vector, as a reference location 73, and
determine first layer neighboring pixel locations based on the
reference location 73.
[0259] That is, when the location indicated by the disparity vector
is a sub-pel location, the inter-layer video decoding apparatus 20
may determine the closest integer-pel location to the sub-pel
location, as the reference location 73. This principle may be the
same as that of the method described above in relation to FIG. 6B.
Alternatively, the inter-layer video decoding apparatus 20 may
determine an integer-pel location based on the location indicated
by the disparity vector, as the reference location 73 according to
the method described above in relation to FIG. 6A or 6C.
[0260] The first layer neighboring pixel locations may be
integer-pel locations, x component values or y component values of
which are smaller than that of the reference location 73 by 1. In
this case, the first layer neighboring pixel locations may not be
the closest integer-pel locations to a top or left side of the
first layer reference block 71.
[0261] According to another embodiment, in FIG. 7B, when the
disparity vector indicates a sub-pel location, the inter-layer
video decoding apparatus 20 may determine the reference location by
using the sub-pel location indicated by the disparity vector, to
improve accuracy of an illumination compensation parameter and thus
to increase coding efficiency. That is, the first layer reference
location may be the sub-pel location indicated by the disparity
vector.
[0262] Referring to FIG. 7B, a reference block 75 of the first
layer image is shown. The reference block 75 may be a 4.times.4
block. The inter-layer video decoding apparatus 20 may determine a
block having a top-left corner location corresponding to a location
indicated by the disparity vector of the second layer current
block, as the reference block 75.
[0263] That is, even when the disparity vector indicates a sub-pel
location, the first layer reference block corresponding to the
second layer current block is determined as a block having a
top-left corner location corresponding to the sub-pel location, the
first layer neighboring pixel locations may also be determined
based on the sub-pel location and thus accuracy of the illumination
compensation parameter may be improved.
[0264] The inter-layer video decoding apparatus 20 may determine
the location indicated by the disparity vector, as a reference
location 77, and determine the first layer neighboring pixel
locations based on the reference location 77. That is, when the
location indicated by the disparity vector is a sub-pel location,
the inter-layer video decoding apparatus 20 may determine the
sub-pel location as the reference location 77.
[0265] The first layer neighboring pixel locations may be sub-pel
locations, x component values or y component values of which are
smaller than that of the reference location 77 by 1.
[0266] FIG. 7C illustrates examples of a method of determining a
reference location to determine first layer neighboring sample
values, according to various embodiments.
[0267] When the location indicated by the disparity vector of the
second layer current block is a sub-pel location, the inter-layer
video decoding apparatus 20 according to various embodiments may
determine the sub-pel location as the reference location, and
determine first layer neighboring sample locations based on the
reference location. In this case, the first layer neighboring
sample locations may be sub-pel locations.
[0268] Referring to FIG. 7C, when the reference location indicated
by the disparity vector is a sub-pel location, the inter-layer
video decoding apparatus 20 according to various embodiments may
express the reference location by using an integer coordinate
(xRLX, yRLX) and a fractional coordinate (xFrac, yFrac) as shown by
the following pseudo-code.
xRLX=xC+((mvLX[0])>>(2+(cldx ? 1: 0)))
yRLX=yC+((mvLX[1])>>(2+(cldx ? 1: 0)))
xFrac=mvLX[0] &(cldx ? 7: 3)
yFrac=mvLX[1] &(cldx ? 7: 3)
[0269] In the above pseudo-code, mvLX[0] and mvLX[1] may denote an
x component and a y component of the disparity vector, (xC, yC) may
denote a location coordinate of the current block, and cldx may
denote a Y component or a depth map when the value thereof is 0,
denote a U component when the value thereof is 1, and denote a V
component when the value thereof is 2. A luma block and a chroma
block have different sizes and thus may have different distances
between integer-pixels. Thus, when the disparity vector indicates a
sub-pixel, the method of determining the reference location may
differ based on whether a conditional "cldx? 1: 0" indicates a luma
block or a chroma block.
[0270] Referring to FIG. 7C, integer-pel samples A, B, C, and D
adjacent to the first layer reference location are shown. The
inter-layer video decoding apparatus 20 may determine first layer
neighboring sample values (refSample) based on the reference
location indicated by the disparity vector, by using the integer
coordinate (xRLX, yRLX) and the fractional coordinate (xFrac,
yFrac) of the reference location and the integer-pel samples A, B,
C, and D adjacent to the reference location. The first layer
neighboring sample values (refSample) may be calculated as shown by
the following pseudo-code.
refSample=((w-xFrac)*(w-yFrac)*refSampleList[4*i]+xFrac*(w-yFrac)*refSam-
pleList[4*i+1]+(w-xFrac)*yFrac*refSampleList[4*i+2]+xFrac*yFrac*refSampleL-
ist[4*i+3]+(cldx==0 ? 8: 32))>>(cldx==0 ? 4: 6)
[0271] In the above pseudo-code, w denotes the size of a 1.times.1
block based on a sub-pel unit, and may have a value of 4 when the
value of cldx is 0, and have a value of 8 when the value of cldx is
not 0. Furthermore, cldx may denote a Y component or a depth map
when the value thereof is 0, denote a U component when the value
thereof is 1, and denote a V component when the value thereof is 2.
In addition, i may have a value ranging from 0 to (No. of Samples
included in Illumination Compensation Sample List/2)-1. Besides,
refSampleList[4*i], refSampleList[4*i+1], refSampleList[4*i+2], and
refSampleList[4*i+3] may be sample values of the locations A, B, C,
and D, respectively.
[0272] When the disparity vector indicates a sub-pel location, the
inter-layer video decoding apparatus 20 may determine the sub-pel
location as the reference location and use the neighboring sample
values determined based on the reference location, thereby
improving accuracy of an illumination compensation parameter and
increasing coding efficiency.
[0273] Although the inter-layer video decoding apparatus 20
determines the first layer reference location in FIGS. 7A to 7C, it
will be understood by one of ordinary skill in the art that the
methods described above in relation to FIGS. 7A to 7C are also
applicable to the inter-layer video encoding apparatus 10.
[0274] As described above, the inter-layer video encoding apparatus
10 according to an embodiment and the inter-layer video decoding
apparatus 20 according to an embodiment may spilt blocks of video
data into coding units having a tree structure, and coding units,
prediction units, and transformation units may be used for
inter-layer prediction or inter prediction of coding units.
Hereinafter, with reference to FIGS. 8 through 20, a video encoding
method, a video encoding apparatus, a video decoding method, and a
video decoding apparatus based on coding units having a tree
structure and transformation units, according to an embodiment,
will be described.
[0275] In principle, during encoding and decoding processes for a
multilayer video, encoding and decoding processes for first layer
images and encoding and decoding processes for second layer images
are separately performed. That is, when inter-layer prediction is
performed on a multilayer video, encoding and decoding results of
single-layer videos may be mutually referred to, but separate
encoding and decoding processes are performed according to
single-layer videos.
[0276] Accordingly, since video encoding and decoding processes
based on coding units having a tree structure as described below
with reference to FIGS. 8 through 20 for convenience of description
are video encoding and decoding processes for processing a
single-layer video, only inter prediction and motion compensation
are performed. However, as described above with reference to FIGS.
1A through 7B, in order to encode and decode a video stream,
inter-layer prediction and compensation are performed on base layer
images and second layer images.
[0277] Accordingly, in order for the encoder 12 of the inter-layer
video encoding apparatus 10 according to an embodiment to encode a
multilayer video based on coding units having a tree structure, the
inter-layer video encoding apparatus 10 may include as many video
encoding apparatuses 100 of FIG. 8 as the number of layers of the
multilayer video so as to perform video encoding according to each
single-layer video, thereby controlling each video encoding
apparatus 100 to encode an assigned single-layer video. Also, the
inter-layer video encoding apparatus 10 may perform inter-view
prediction by using encoding results of individual single
viewpoints of each video encoding apparatus 100. Accordingly, the
encoder 12 of the inter-layer video encoding apparatus 10 may
generate a base view video stream and a second layer video stream,
which include encoding results according to layers.
[0278] Similarly, in order for the decoder 24 of the inter-layer
video decoding apparatus 20 according to an embodiment to decode a
multilayer video based on coding units having a tree structure, the
inter-layer video decoding apparatus 20 may include as many video
decoding apparatuses 200 of FIG. 9 as the number of layers of the
multilayer video so as to perform video decoding according to
layers with respect to a received first layer video stream and a
received second layer video stream, thereby controlling each video
decoding apparatus 200 to decode an assigned single-layer video.
Also, the inter-layer video decoding apparatus 20 may perform
inter-layer compensation by using a decoding result of an
individual single layer of each video decoding apparatus 200.
Accordingly, the decoder 24 of the inter-layer video decoding
apparatus 20 may generate first layer images and second layer
images, which are reconstructed according to layers.
[0279] FIG. 8 is a block diagram of the video encoding apparatus
based on coding units according to a tree structure 100, according
to an embodiment of the present disclosure.
[0280] The video encoding apparatus involving video prediction
based on coding units according to a tree structure 100 according
to an embodiment includes a largest coding unit splitter 110, a
coding unit determiner 120, and an output unit 130. Hereinafter,
for convenience of description, the video encoding apparatus
involving video prediction based on coding units according to a
tree structure 100 will be abbreviated to the `video encoding
apparatus 100`.
[0281] The coding unit determiner 120 may split a current picture
based on a largest coding unit that is a coding unit having a
maximum size for the current picture of an image. If the current
picture is larger than the largest coding unit, image data of the
current picture may be split into the at least one largest coding
unit. The largest coding unit according to an embodiment may be a
data unit having a size of 32.times.32, 64.times.64, 128.times.128,
256.times.256, etc., wherein a shape of the data unit is a square
having a width and length in squares of 2.
[0282] A coding unit according to an embodiment may be
characterized by a maximum size and a depth. The depth denotes the
number of times the coding unit is spatially split from the largest
coding unit, and as the depth deepens, deeper coding units
according to depths may be split from the largest coding unit to a
minimum coding unit. A depth of the largest coding unit is an
uppermost depth and a depth of the minimum coding unit is a
lowermost depth. Since a size of a coding unit corresponding to
each depth decreases as the depth of the largest coding unit
deepens, a coding unit corresponding to an upper depth may include
a plurality of coding units corresponding to lower depths.
[0283] As described above, the image data of the current picture is
split into the largest coding units according to a maximum size of
the coding unit, and each of the largest coding units may include
deeper coding units that are split according to depths. Since the
largest coding unit according to an embodiment is split according
to depths, the image data of a spatial domain included in the
largest coding unit may be hierarchically classified according to
depths.
[0284] A maximum depth and a maximum size of a coding unit, which
limit the total number of times a height and a width of the largest
coding unit are hierarchically split, may be predetermined.
[0285] The coding unit determiner 120 encodes at least one split
region obtained by splitting a region of the largest coding unit
according to depths, and determines a depth to output a finally
encoded image data according to the at least one split region. In
other words, the coding unit determiner 120 determines a final
depth by encoding the image data in the deeper coding units
according to depths, according to the largest coding unit of the
current picture, and selecting a depth having the minimum encoding
error. The determined final depth and the encoded image data
according to the determined coded depth are output to the output
unit 130.
[0286] The image data in the largest coding unit is encoded based
on the deeper coding units corresponding to at least one depth
equal to or below the maximum depth, and results of encoding the
image data are compared based on each of the deeper coding units. A
depth having the minimum encoding error may be selected after
comparing encoding errors of the deeper coding units. At least one
final depth may be selected for each largest coding unit.
[0287] The size of the largest coding unit is split as a coding
unit is hierarchically split according to depths, and as the number
of coding units increases. Also, even if coding units correspond to
the same depth in one largest coding unit, it is determined whether
to split each of the coding units corresponding to the same depth
to a lower depth by measuring an encoding error of the image data
of the each coding unit, separately. Accordingly, even when image
data is included in one largest coding unit, the encoding errors
may differ according to regions in the one largest coding unit, and
thus the final depths may differ according to regions in the image
data. Thus, one or more final depths may be determined in one
largest coding unit, and the image data of the largest coding unit
may be divided according to coding units of at least one final
depth.
[0288] Accordingly, the coding unit determiner 120 according to an
embodiment may determine coding units having a tree structure
included in the largest coding unit. The `coding units having a
tree structure` according to an embodiment include coding units
corresponding to a depth determined to be the final depth, from
among all deeper coding units included in the largest coding unit.
A coding unit of a final depth may be hierarchically determined
according to depths in the same region of the largest coding unit,
and may be independently determined in different regions.
Similarly, a final depth in a current region may be independently
determined from a final depth in another region.
[0289] A maximum depth according to an embodiment is an index
related to the number of splitting times from a largest coding unit
to a minimum coding unit. A first maximum depth according to an
embodiment may denote the total number of splitting times from the
largest coding unit to the minimum coding unit. A second maximum
depth according to an embodiment may denote the total number of
depth levels from the largest coding unit to the minimum coding
unit. For example, when a depth of the largest coding unit is 0, a
depth of a coding unit, in which the largest coding unit is split
once, may be set to 1, and a depth of a coding unit, in which the
largest coding unit is split twice, may be set to 2. In this case,
if the minimum coding unit is a coding unit in which the largest
coding unit is split four times, depth levels of depths 0, 1, 2, 3,
and 4 exist, and thus the first maximum depth may be set to 4, and
the second maximum depth may be set to 5.
[0290] Prediction encoding and transformation may be performed
according to the largest coding unit. The prediction encoding and
the transformation are also performed based on the deeper coding
units according to a depth equal to or depths less than the maximum
depth, according to the largest coding unit.
[0291] Since the number of deeper coding units increases whenever
the largest coding unit is split according to depths, encoding,
including the prediction encoding and the transformation, is
performed on all of the deeper coding units generated as the depth
deepens. For convenience of description, the prediction encoding
and the transformation will now be described based on a coding unit
of a current depth, in a largest coding unit.
[0292] The video encoding apparatus 100 according to an embodiment
may variously select a size or shape of a data unit for encoding
the image data. In order to encode the image data, operations, such
as prediction encoding, transformation, and entropy encoding, are
performed, and at this time, the same data unit may be used for all
operations or different data units may be used for each
operation.
[0293] For example, the video encoding apparatus 100 may select not
only a coding unit for encoding the image data, but also a data
unit different from the coding unit so as to perform the prediction
encoding on the image data in the coding unit.
[0294] In order to perform prediction encoding in the largest
coding unit, the prediction encoding may be performed based on a
coding unit corresponding to a final depth according to an
embodiment, i.e., based on a coding unit that is no longer split to
coding units corresponding to a lower depth. Hereinafter, the
coding unit that is no longer split and becomes a basis unit for
prediction encoding will now be referred to as a `prediction unit`.
A partition obtained by splitting the prediction unit may include a
prediction unit and a data unit obtained by splitting at least one
of a height and a width of the prediction unit. A partition is a
data unit where a prediction unit of a coding unit is split, and a
prediction unit may be a partition having the same size as a coding
unit.
[0295] For example, when a coding unit of 2N.times.2N (where N is a
positive integer) is no longer split and becomes a prediction unit
of 2N.times.2N, and a size of a partition may be 2N.times.2N,
2N.times.N, N.times.2N, or N.times.N. Examples of a partition mode
according to an embodiment may selectively include symmetrical
partitions that are obtained by symmetrically splitting a height or
width of the prediction unit, partitions obtained by asymmetrically
splitting the height or width of the prediction unit, such as 1:n
or n:1, partitions that are obtained by geometrically splitting the
prediction unit, and partitions having arbitrary shapes.
[0296] A prediction mode of the prediction unit may be at least one
of an intra mode, a inter mode, and a skip mode. For example, the
intra mode or the inter mode may be performed on the partition of
2N.times.2N, 2N.times.N, N.times.2N, or N.times.N. Also, the skip
mode may be performed only on the partition of 2N.times.2N. The
encoding is independently performed on one prediction unit in a
coding unit, thereby selecting a prediction mode having a minimum
encoding error.
[0297] The video encoding apparatus 100 according to an embodiment
may also perform the transformation on the image data in a coding
unit based not only on the coding unit for encoding the image data,
but also based on a data unit that is different from the coding
unit. In order to perform the transformation in the coding unit,
the transformation may be performed based on a transformation unit
having a size less than or equal to the coding unit. For example,
the transformation unit may include a data unit for an intra mode
and a transformation unit for an inter mode.
[0298] The transformation unit in the coding unit may be
recursively split into smaller sized regions in a manner similar to
that in which the coding unit is split according to the tree
structure, according to an embodiment. Thus, residual data in the
coding unit may be split according to the transformation unit
having the tree structure according to transformation depths.
[0299] A transformation depth indicating the number of splitting
times to reach the transformation unit by splitting the height and
width of the coding unit may also be set in the transformation unit
according to an embodiment. For example, in a current coding unit
of 2N.times.2N, a transformation depth may be 0 when the size of a
transformation unit is 2N.times.2N, may be 1 when the size of the
transformation unit is N.times.N, and may be 2 when the size of the
transformation unit is N/2.times.N/2. That is, the transformation
unit having the tree structure may be set according to the
transformation depths.
[0300] Split information according to depths requires not only
information about a depth, but also about information related to
prediction encoding and transformation. Accordingly, the coding
unit determiner 120 not only determines a depth having a minimum
encoding error, but also determines a partition mode of splitting a
prediction unit into a partition, a prediction mode according to
prediction units, and a size of a transformation unit for
transformation.
[0301] Coding units according to a tree structure in a largest
coding unit and methods of determining a prediction unit/partition,
and a transformation unit, according to various embodiments, will
be described in detail below with reference to FIGS. 9 through
19.
[0302] The coding unit determiner 120 may measure an encoding error
of deeper coding units according to depths by using Rate-Distortion
Optimization based on Lagrangian multipliers.
[0303] The output unit 130 outputs the image data of the largest
coding unit, which is encoded based on the at least one depth
determined by the coding unit determiner 120, and split information
according to the depth, in bitstreams.
[0304] The encoded image data may be obtained by encoding residual
data of an image.
[0305] The split information according to depth may include
information about the depth, about the partition mode in the
prediction unit, about the prediction mode, and about split of the
transformation unit.
[0306] The information about the final depth may be defined by
using split information according to depths, which indicates
whether encoding is performed on coding units of a lower depth
instead of a current depth. If the current depth of the current
coding unit is a depth, the current coding unit is encoded, and
thus the split information may be defined not to split the current
coding unit to a lower depth. On the other hand, if the current
depth of the current coding unit is not the depth, the encoding is
performed on the coding unit of the lower depth, and thus the split
information may be defined to split the current coding unit to
obtain the coding units of the lower depth.
[0307] If the current depth is not the depth, encoding is performed
on the coding unit that is split into the coding unit of the lower
depth. Since at least one coding unit of the lower depth exists in
one coding unit of the current depth, the encoding is repeatedly
performed on each coding unit of the lower depth, and thus the
encoding may be recursively performed for the coding units having
the same depth.
[0308] Since the coding units having a tree structure are
determined for one largest coding unit, and split information is
determined for a coding unit of a depth, at least one piece of
split information may be determined for one largest coding unit.
Also, a depth of the image data of the largest coding unit may be
different according to locations since the image data is
hierarchically split according to depths, and thus a depth and
split information may be set for the image data.
[0309] Accordingly, the output unit 130 according to an embodiment
may assign a corresponding depth and encoding information about an
encoding mode to at least one of the coding unit, the prediction
unit, and a minimum unit included in the largest coding unit.
[0310] The minimum unit according to an embodiment is a square data
unit obtained by splitting the minimum coding unit constituting the
lowermost depth by 4. Alternatively, the minimum unit according to
an embodiment may be a maximum square data unit that may be
included in all of the coding units, prediction units, partition
units, and transformation units included in the largest coding
unit.
[0311] For example, the encoding information output by the output
unit 130 may be classified into encoding information according to
deeper coding units, and encoding information according to
prediction units. The encoding information according to the deeper
coding units may include the information about the prediction mode
and about the size of the partitions. The encoding information
according to the prediction units may include information about an
estimated direction of an inter mode, about a reference image index
of the inter mode, about a motion vector, about a chroma component
of an intra mode, and about an interpolation method of the intra
mode.
[0312] Information about a maximum size of the coding unit defined
according to pictures, slices, or GOPs, and information about a
maximum depth may be inserted into a header of a bitstream, a
sequence parameter set, or a picture parameter set.
[0313] Information about a maximum size of the transformation unit
allowed with respect to a current video, and information about a
minimum size of the transformation unit may also be output through
a header of a bitstream, a sequence parameter set, or a picture
parameter set. The output unit 130 may encode and output reference
information related to prediction, prediction information, and
slice type information.
[0314] In the video encoding apparatus 100 according to the
simplest embodiment, the deeper coding unit may be a coding unit
obtained by dividing a height or width of a coding unit of an upper
depth, which is one layer above, by two. That is, when the size of
the coding unit of the current depth is 2N.times.2N, the size of
the coding unit of the lower depth is N.times.N. Also, a current
coding unit having a size of 2N.times.2N may maximally include four
lower-depth coding units each having a size of N.times.N.
[0315] Accordingly, the video encoding apparatus 100 may form the
coding units having the tree structure by determining coding units
having an optimum shape and an optimum size for each largest coding
unit, based on the size of the largest coding unit and the maximum
depth determined considering characteristics of the current
picture. Also, since encoding may be performed on each largest
coding unit by using any one of various prediction modes and
transformations, an optimum encoding mode may be determined
considering characteristics of the coding unit of various image
sizes.
[0316] Thus, if an image having a high resolution or a large data
amount is encoded in a conventional macroblock, the number of
macroblocks per picture excessively increases. Accordingly, the
number of pieces of compressed information generated for each
macroblock increases, and thus it is difficult to transmit the
compressed information and data compression efficiency decreases.
However, by using the video encoding apparatus 100 according to an
embodiment, image compression efficiency may be increased since a
coding unit is adjusted while considering characteristics of an
image while increasing a maximum size of a coding unit while
considering a size of the image.
[0317] The inter-layer video encoding apparatus 10 described above
with reference to FIG. 1A may include as many video encoding
apparatuses 100 as the number of layers, in order to encode
single-layer images according to layers of a multilayer video. For
example, the first layer encoder 12 may include one video encoding
apparatus 100 and the second layer encoder 14 may include as many
video encoding apparatuses 100 as the number of second layers.
[0318] When the video encoding apparatus 100 encodes first layer
images, the coding unit determiner 120 may determine, for each
largest coding unit, a prediction unit for inter-prediction
according to coding units having a tree structure, and perform
inter-prediction according to prediction units.
[0319] Even when the video encoding apparatus 100 encodes second
layer images, the coding unit determiner 120 may determine, for
each largest coding unit, coding units and prediction units having
a tree structure, and perform inter-prediction according to
prediction units.
[0320] The video encoding apparatus 100 may encode a luminance
difference to compensate for a luminance difference between a first
layer image and a second layer image. However, whether to perform
luminance may be determined according to an encoding mode of a
coding unit. For example, luminance compensation may be performed
only on a prediction unit having a size of 2N.times.2N.
[0321] FIG. 9 is a block diagram of the video decoding apparatus
based on coding units according to a tree structure 200, according
to various embodiments.
[0322] The video decoding apparatus that involves video prediction
based on coding units having a tree structure 200 according to an
embodiment includes a receiver 210, an image data and encoding
information extractor 220, and an image data decoder 230. For
convenience of description, the video decoding apparatus that
involves video prediction based on coding units having a tree
structure 200 according to an embodiment will be abbreviated to the
`video decoding apparatus 200`.
[0323] Definitions of various terms, such as a coding unit, a
depth, a prediction unit, a transformation unit, and various split
information, for decoding operations of the video decoding
apparatus 200 according to an embodiment are identical to those
described with reference to FIG. 8 and the video encoding apparatus
100.
[0324] The receiver 210 receives and parses a bitstream of an
encoded video. The image data and encoding information extractor
220 extracts encoded image data for each coding unit from the
parsed bitstream, wherein the coding units have a tree structure
according to each largest coding unit, and outputs the extracted
image data to the image data decoder 230. The image data and
encoding information extractor 220 may extract information about a
maximum size of a coding unit of a current picture, from a header
about the current picture, a sequence parameter set, or a picture
parameter set.
[0325] Also, the image data and encoding information extractor 220
extracts a final depth and split information for the coding units
having a tree structure according to each largest coding unit, from
the parsed bitstream. The extracted final depth and split
information are output to the image data decoder 230. That is, the
image data in a bit stream is split into the largest coding unit so
that the image data decoder 230 decodes the image data for each
largest coding unit.
[0326] A depth and split information according to the largest
coding unit may be set for at least one piece of depth information,
and split information may include information about a partition
mode of a corresponding coding unit, about a prediction mode, and
about split of a transformation unit. Also, split information
according to depths may be extracted as the information about a
depth.
[0327] The depth and the split information according to each
largest coding unit extracted by the image data and encoding
information extractor 220 is a depth and split information
determined to generate a minimum encoding error when an encoder,
such as the video encoding apparatus 100 according to an
embodiment, repeatedly performs encoding for each deeper coding
unit according to depths according to each largest coding unit.
Accordingly, the video decoding apparatus 200 may reconstruct an
image by decoding the image data according to a coded depth and an
encoding mode that generates the minimum encoding error.
[0328] Since encoding information about a depth and an encoding
mode according to an embodiment may be assigned to a predetermined
data unit from among a corresponding coding unit, a prediction
unit, and a minimum unit, the image data and encoding information
extractor 220 may extract the depth and the split information
according to the predetermined data units. If the depth and the
split information of a corresponding largest coding unit is
recorded according to predetermined data units, the predetermined
data units to which the same depth and the same split information
is assigned may be inferred to be the data units included in the
same largest coding unit.
[0329] The image data decoder 230 may reconstruct the current
picture by decoding the image data in each largest coding unit
based on the depth and the split information according to the
largest coding units. That is, the image data decoder 230 may
decode the encoded image data based on the extracted information
about the partition mode, the prediction mode, and the
transformation unit for each coding unit from among the coding
units having the tree structure included in each largest coding
unit. A decoding process may include a prediction including intra
prediction and motion compensation, and an inverse
transformation.
[0330] The image data decoder 230 may perform intra prediction or
motion compensation according to a partition and a prediction mode
of each coding unit, based on the information about the partition
mode and the prediction mode of the prediction unit of the coding
unit according to depths.
[0331] In addition, the image data decoder 230 may read information
about a transformation unit according to a tree structure for each
coding unit so as to perform inverse transformation based on
transformation units for each coding unit, for inverse
transformation for each largest coding unit. Via the inverse
transformation, a pixel value of a spatial domain of the coding
unit may be reconstructed.
[0332] The image data decoder 230 may determine a depth of a
current largest coding unit by using split information according to
depths. If the split information indicates that image data is no
longer split in the current depth, the current depth is a depth.
Accordingly, the image data decoder 230 may decode encoded data in
the current largest coding unit by using the information about the
partition mode of the prediction unit, the prediction mode, and the
size of the transformation unit.
[0333] That is, data units containing the encoding information
including the same split information may be gathered by observing
the encoding information set assigned for the predetermined data
unit from among the coding unit, the prediction unit, and the
minimum unit, and the gathered data units may be considered to be
one data unit to be decoded by the image data decoder 230 in the
same encoding mode. As such, the current coding unit may be decoded
by obtaining the information about the encoding mode for each
coding unit.
[0334] The inter-layer video decoding apparatus 20 described above
with reference to FIG. 2A may include the number of video decoding
apparatuses 200 as much as the number of viewpoints, so as to
reconstruct first layer images and second layer images by decoding
a received first layer image stream and a received second layer
image stream.
[0335] When the first layer image stream is received, the image
data decoder 230 of the video decoding apparatus 200 may split
samples of first layer images extracted from the first layer image
stream by the image data and encoding information extractor 220
into coding units having a tree structure. The image data decoder
230 may reconstruct the first layer images by performing motion
compensation according to prediction units for inter prediction, on
the coding units having the tree structure obtained by splitting
the samples of the first layer images.
[0336] When the second layer image stream is received, the image
data decoder 230 of the video decoding apparatus 200 may split
samples of second layer images extracted from the second layer
image stream by the image data and encoding information extractor
220 into coding units having a tree structure. The image data
decoder 230 may reconstruct the second layer images by performing
motion compensation according to prediction units for inter
prediction, on the coding units obtained by splitting the samples
of the second layer images.
[0337] The extractor 220 may obtain information related to a
luminance error from a bitstream so as to compensate for a
luminance difference between a first layer image and a second layer
image. However, whether to perform luminance may be determined
according to an encoding mode of a coding unit. For example,
luminance compensation may be performed only on a prediction unit
having a size of 2N.times.2N.
[0338] Thus, the video decoding apparatus 200 may obtain
information about at least one coding unit that generates the
minimum encoding error when encoding is recursively performed for
each largest coding unit, and may use the information to decode the
current picture. In other words, the coding units having the tree
structure determined to be the optimum coding units in each largest
coding unit may be decoded.
[0339] Accordingly, even if image data has high resolution and a
large amount of data, the image data may be efficiently decoded and
reconstructed by using a size of a coding unit and an encoding
mode, which are adaptively determined according to characteristics
of the image data, by using optimum split information received from
an encoder.
[0340] FIG. 10 is a diagram for describing a concept of coding
units, according to various embodiments.
[0341] A size of a coding unit may be expressed by
width.times.height, and may be 64.times.64, 32.times.32,
16.times.16, and 8.times.8. A coding unit of 64.times.64 may be
split into partitions of 64.times.64, 64.times.32, 32.times.64, or
32.times.32, and a coding unit of 32.times.32 may be split into
partitions of 32.times.32, 32.times.16, 16.times.32, or
16.times.16, a coding unit of 16.times.16 may be split into
partitions of 16.times.16, 16.times.8, 8.times.16, or 8.times.8,
and a coding unit of 8.times.8 may be split into partitions of
8.times.8, 8.times.4, 4.times.8, or 4.times.4.
[0342] In video data 310, a resolution is 1920.times.1080, a
maximum size of a coding unit is 64, and a maximum depth is 2. In
video data 320, a resolution is 1920.times.1080, a maximum size of
a coding unit is 64, and a maximum depth is 3. In video data 330, a
resolution is 352.times.288, a maximum size of a coding unit is 16,
and a maximum depth is 1. The maximum depth shown in FIG. 10
denotes a total number of splits from a largest coding unit to a
minimum decoding unit.
[0343] If a resolution is high or a data amount is large, a maximum
size of a coding unit may be large so as to not only increase
encoding efficiency but also to accurately reflect characteristics
of an image. Accordingly, the maximum size of the coding unit of
the video data 310 and 320 having a higher resolution than the
video data 330 may be 64.
[0344] Since the maximum depth of the video data 310 is 2, coding
units 315 of the vide data 310 may include a largest coding unit
having a long axis size of 64, and coding units having long axis
sizes of 32 and 16 since depths are deepened to two layers by
splitting the largest coding unit twice. Since the maximum depth of
the video data 330 is 1, coding units 335 of the video data 330 may
include a largest coding unit having a long axis size of 16, and
coding units having a long axis size of 8 since depths are deepened
to one layer by splitting the largest coding unit once.
[0345] Since the maximum depth of the video data 320 is 3, coding
units 325 of the video data 320 may include a largest coding unit
having a long axis size of 64, and coding units having long axis
sizes of 32, 16, and 8 since the depths are deepened to 3 layers by
splitting the largest coding unit three times. As a depth deepens,
detailed information may be precisely expressed.
[0346] FIG. 11 is a block diagram of an image encoder 400 based on
coding units, according to various embodiments.
[0347] The image encoder 400 according to an embodiment performs
operations of the coding unit determiner 120 of the video encoding
apparatus 100 to encode image data. In other words, an intra
predictor 420 performs intra prediction on coding units in an intra
mode, from among a current frame 405, per prediction unit, and an
inter predictor 415 performs inter prediction on coding units in an
inter mode by using the current image 405 and a reference image
obtained by a restored picture buffer 410, per prediction unit. The
current picture 405 may be split into largest coding units, and
then the largest coding units may be sequentially encoded. Here,
the encoding may be performed on coding units split in a tree
structure from the largest coding unit.
[0348] Residual data is generated by subtracting prediction data of
a coding unit of each mode output from the intra predictor 420 or
the inter predictor 415 from data of the current image 405 to be
encoded, and the residual data is output as a quantized
transformation coefficient through a transformer 425 and a
quantizer 430 per transformation unit. The quantized transformation
coefficient is restored to residual data in a spatial domain
through an inverse quantizer 445 and an inverse transformer 450.
The residual data in the spatial domain is added to the prediction
data of the coding unit of each mode output from the intra
predictor 420 or the inter predictor 415 to be restored as data in
a spatial domain of the coding unit of the current image 405. The
data in the spatial domain passes through a deblocker 455 and a
sample adaptive offset (SAO) performer 460 and thus a restored
image is generated. The restored image is stored in the restored
picture buffer 410. Restored images stored in the restored picture
buffer 410 may be used as a reference image for inter prediction of
another image. The quantized transformation coefficient obtained
through the transformer 425 and the quantizer 430 may be output as
a bitstream 440 through an entropy encoder 435.
[0349] In order for the image encoder 400 according to an
embodiment to be applied in the video encoding apparatus 100,
components of the image encoder 400, i.e., the inter predictor 415,
the intra predictor 420, the transformer 425, the quantizer 430,
the entropy encoder 435, the inverse quantizer 445, the inverse
transformer 450, the deblocking unit 455, and the SAO performer 460
perform operations based on each coding unit among coding units
having a tree structure per largest coding unit.
[0350] In particular, the intra predictor 420 and the inter
predictor 415 determine partitions and a prediction mode of each
coding unit from among the coding units having a tree structure
while considering the maximum size and the maximum depth of a
current largest coding unit, and the transformer 425 may determine
whether to split a transformation unit according to a quad-tree in
each coding unit from among the coding units having the tree
structure.
[0351] FIG. 12 is a block diagram of an image decoder 500 based on
coding units, according to various embodiments.
[0352] An entropy decoder 515 parses encoded image data that is to
be decoded and encoding information required for decoding from a
bitstream 505. The encoded image data is a quantized transformation
coefficient, and an inverse quantizer 520 and an inverse
transformer 525 restores residual data from the quantized
transformation coefficient.
[0353] An intra predictor 540 performs intra prediction on a coding
unit in an intra mode according to prediction units. An inter
predictor performs inter prediction on a coding unit in an inter
mode from a current image according to prediction units, by using a
reference image obtained by a restored picture buffer 530.
[0354] Data in a spatial domain of coding units of the current
image is restored by adding the residual data and the prediction
data of a coding unit of each mode through the intra predictor and
the inter predictor 535, and the data in the spatial domain may be
output as a restored image through a deblocking unit 545 and an SAO
performer 550. Also, restored images stored in the restored picture
buffer 530 may be output as reference images.
[0355] In order to decode the image data in the image data decoder
230 of the video decoding apparatus 200, operations after the
entropy decoder 515 of the image decoder 500 according to an
embodiment may be performed.
[0356] In order for the image decoder 500 to be applied in the
video decoding apparatus 200 according to an embodiment, components
of the image decoder 500, i.e., the entropy decoder 515, the
inverse quantizer 520, the inverse transformer 525, the intra
predictor 540, the inter predictor 535, the deblocking unit 545,
and the SAO performer 550 may perform operations based on coding
units having a tree structure for each largest coding unit.
[0357] In particular, the intra predictor 540 and the inter
predictor 535 determine a partition mode and a prediction mode
according to each of coding units having a tree structure, and the
inverse transformer 525 may determine whether to split a
transformation unit according to a quad-tree structure per coding
unit.
[0358] An encoding operation of FIG. 10 and a decoding operation of
FIG. 11 are respectively a video stream encoding operation and a
video stream decoding operation in a single layer. Accordingly,
when the encoder 12 of FIG. 1 A encodes a video stream of at least
two layers, the video encoding apparatus 100 of FIG. 1A may include
as many image encoder 400 as the number of layers. Similarly, when
the decoder 24 of FIG. 2A decodes a video stream of at least two
layers, the video decoding apparatus 200 of FIG. 2A may include as
many image decoders 500 as the number of layers.
[0359] FIG. 13 is a diagram illustrating coding units and
partitions, according to various embodiments.
[0360] The video encoding apparatus 100 according to an embodiment
and the video decoding apparatus 200 according to an embodiment use
hierarchical coding units so as to consider characteristics of an
image. A maximum height, a maximum width, and a maximum depth of
coding units may be adaptively determined according to the
characteristics of the image, or may be variously set according to
user requirements. Sizes of deeper coding units according to depths
may be determined according to the predetermined maximum size of
the coding unit.
[0361] In a hierarchical structure 600 of coding units according to
an embodiment, the maximum height and the maximum width of the
coding units are each 64, and the maximum depth is 3. In this case,
the maximum depth refers to a total number of times the coding unit
is split from the largest coding unit to the minimum coding unit.
Since a depth deepens along a vertical axis of the hierarchical
structure 600 of coding units according to an embodiment, a height
and a width of the deeper coding unit are each split. Also, a
prediction unit and partitions, which are bases for prediction
encoding of each deeper coding unit, are shown along a horizontal
axis of the hierarchical structure 600.
[0362] That is, a coding unit 610 is a largest coding unit in the
hierarchical structure 600, wherein a depth is 0 and a size, i.e.,
a height by width, is 64.times.64. The depth deepens along the
vertical axis, and a coding unit 620 having a size of 32.times.32
and a depth of 1, a coding unit 630 having a size of 16.times.16
and a depth of 2, and a coding unit 640 having a size of 8.times.8
and a depth of 3. The coding unit 640 having a size of 8.times.8
and a depth of 3 is a minimum coding unit.
[0363] The prediction unit and the partitions of a coding unit are
arranged along the horizontal axis according to each depth. That
is, if the coding unit 610 having a size of 64.times.64 and a depth
of 0 is a prediction unit, the prediction unit may be split into
partitions included in the encoding unit 610 having a size of
64.times.64, i.e. a partition 610 having a size of 64.times.64,
partitions 612 having the size of 64.times.32, partitions 614
having the size of 32.times.64, or partitions 616 having the size
of 32.times.32.
[0364] Equally, a prediction unit of the coding unit 620 having the
size of 32.times.32 and the depth of 1 may be split into partitions
included in the coding unit 620 having the size of 32.times.32,
i.e. a partition 620 having a size of 32.times.32, partitions 622
having a size of 32.times.16, partitions 624 having a size of
16.times.32, and partitions 626 having a size of 16.times.16.
[0365] Equally, a prediction unit of the coding unit 630 having the
size of 16.times.16 and the depth of 2 may be split into partitions
included in the coding unit 630 having the size of 16.times.16,
i.e. a partition having a size of 16.times.16 included in the
coding unit 630, partitions 632 having a size of 16.times.8,
partitions 634 having a size of 8.times.16, and partitions 636
having a size of 8.times.8.
[0366] Equally, a prediction unit of the coding unit 640 having the
size of 8.times.8 and the depth of 3 may be split into partitions
included in the coding unit 640 having the size of 8.times.8, i.e.
a partition having a size of 8.times.8 included in the coding unit
640, partitions 642 having a size of 8.times.4, partitions 644
having a size of 4.times.8, and partitions 646 having a size of
4.times.4.
[0367] In order to determine the depth of the largest coding unit
610, the coding unit determiner 120 of the video encoding apparatus
100 according to an embodiment performs encoding for coding units
corresponding to each depth included in the maximum coding unit
610.
[0368] A number of deeper coding units according to depths
including data in the same range and the same size increases as the
depth deepens. For example, four coding units corresponding to a
depth of 2 are required to cover data that is included in one
coding unit corresponding to a depth of 1. Accordingly, in order to
compare encoding results of the same data according to depths, the
coding unit corresponding to the depth of 1 and four coding units
corresponding to the depth of 2 are each encoded.
[0369] In order to perform encoding for a current depth from among
the depths, a minimum encoding error may be selected for the
current depth by performing encoding for each prediction unit in
the coding units corresponding to the current depth, along the
horizontal axis of the hierarchical structure 600. Alternatively,
the minimum encoding error may be searched for by comparing the
minimum encoding errors according to depths, by performing encoding
for each depth as the depth deepens along the vertical axis of the
hierarchical structure 600. A depth and a partition having the
minimum encoding error in the largest coding unit 610 may be
selected as the depth and a partition mode of the largest coding
unit 610.
[0370] FIG. 14 is a diagram for describing a relationship between a
coding unit and transformation units, according to various
embodiments.
[0371] The video encoding apparatus 100 according to an embodiment
or the video decoding apparatus 200 according to an embodiment
encodes or decodes an image according to coding units having sizes
less than or equal to a largest coding unit for each largest coding
unit. Sizes of transformation units for transformation during
encoding may be selected based on data units that are not larger
than a corresponding coding unit.
[0372] For example, in the video encoding apparatus 100 according
to an embodiment or the video decoding apparatus 200 according to
an embodiment, if a size of a coding unit 710 is 64.times.64,
transformation may be performed by using a transformation unit 720
having a size of 32.times.32.
[0373] Also, data of the coding unit 710 having the size of
64.times.64 may be encoded by performing the transformation on each
of the transformation units having the size of 32.times.32,
16.times.16, 8.times.8, and 4.times.4, which are smaller than
64.times.64, and then a transformation unit having the least coding
error may be selected.
[0374] FIG. 15 illustrates a plurality of pieces of encoding
information, according to various embodiments.
[0375] The output unit 130 of the video encoding apparatus 100
according to an embodiment may encode and transmit information 800
about a partition mode, information 810 about a prediction mode,
and information 820 about a size of a transformation unit for each
coding unit corresponding to a depth, as split information.
[0376] The information 800 indicates information about a shape of a
partition obtained by splitting a prediction unit of a current
coding unit, wherein the partition is a data unit for prediction
encoding the current coding unit. For example, a current coding
unit CU_0 having a size of 2N.times.2N may be split into any one of
a partition 802 having a size of 2N.times.2N, a partition 804
having a size of 2N.times.N, a partition 806 having a size of
N.times.2N, and a partition 808 having a size of N.times.N. In this
case, the information 800 about a partition type of a current
coding unit is set to indicate one of the partition 804 having a
size of 2N.times.N, the partition 806 having a size of N.times.2N,
and the partition 808 having a size of N.times.N.
[0377] The information 810 indicates a prediction mode of each
partition. For example, the information 810 may indicate a mode of
prediction encoding performed on a partition indicated by the
information 800, i.e., an intra mode 812, an inter mode 814, or a
skip mode 816.
[0378] The information 820 indicates a transformation unit to be
based on when transformation is performed on a current coding unit.
For example, the transformation unit may be a first intra
transformation unit 822, a second intra transformation unit 824, a
first inter transformation unit 826, or a second inter
transformation unit 828.
[0379] The image data and encoding information extractor 220 of the
video decoding apparatus 200 according to an embodiment may extract
and use the information 800, 810, and 820 for decoding, according
to each deeper coding unit.
[0380] FIG. 16 is a diagram of deeper coding units according to
depths, according to various embodiments.
[0381] Split information may be used to indicate a change of a
depth. The spilt information indicates whether a coding unit of a
current depth is split into coding units of a lower depth.
[0382] A prediction unit 910 for prediction encoding a coding unit
900 having a depth of 0 and a size of 2N_0.times.2N_0 may include
partitions of a partition mode 912 having a size of
2N_0.times.2N_0, a partition mode 914 having a size of
2N_0.times.N_0, a partition mode 916 having a size of
N_0.times.2N_0, and a partition mode 918 having a size of
N_0.times.N_0. FIG. 9 only illustrates the partitions 912 through
918 which are obtained by symmetrically splitting the prediction
unit, but a partition mode is not limited thereto, and the
partitions of the prediction unit may include asymmetrical
partitions, partitions having an arbitrary shape, and partitions
having a geometrical shape.
[0383] Prediction encoding is repeatedly performed on one partition
having a size of 2N_0.times.2N_0, two partitions having a size of
2N_0.times.N_0, two partitions having a size of N_0.times.2N_0, and
four partitions having a size of N_0.times.N_0, according to each
partition mode. The prediction encoding in an intra mode and an
inter mode may be performed on the partitions having the sizes of
2N_0.times.2N_0, N_0.times.2N_0, 2N_0.times.N_0, and N_0.times.N_0.
The prediction encoding in a skip mode is performed only on the
partition having the size of 2N_0.times.2N_0.
[0384] If an encoding error in one of the partition modes 912, 914,
and 916 is a minimum error, the prediction unit 910 may not be
split into a lower depth.
[0385] If the encoding error in the partition mode 918 is a minimum
error, a depth is changed from 0 to 1 to split the partition mode
918 in operation 920, and encoding is repeatedly performed on
coding units 930 having a depth of 2 and a size of N_0.times.N_0 to
search for a minimum encoding error.
[0386] A prediction unit 940 for prediction encoding the coding
unit 930 having a depth of 1 and a size of 2N_1.times.2N_1
(=N_0.times.N_0) may include partitions of a partition mode 942
having a size of 2N_1.times.2N_1, a partition mode 944 having a
size of 2N_1.times.N_1, a partition mode 946 having a size of
N_1.times.2N_1, and a partition mode 948 having a size of
N_1.times.N_1.
[0387] If the encoding error in the partition mode 948 is a least
error, a depth is changed from 1 to 2 to split the partition mode
948 in operation 950, and encoding is repeatedly performed on
coding units 960, which have a depth of 2 and a size of
N_2.times.N_2 to search for a minimum encoding error.
[0388] When a maximum depth is d, deeper coding units according to
depths may be set until when a depth corresponds to d-1, and split
information may be set until when a depth corresponds to d-2. That
is, when encoding is performed up to when the depth is d-1 after a
coding unit corresponding to a depth of d-2 is split in operation
970, a prediction unit 990 for prediction encoding a coding unit
980 having a depth of d-1 and a size of 2N_(d-1).times.2N_(d-1) may
include partitions of a partition mode 992 having a size of
2N_(d-1).times.2N_(d-1), a partition mode 994 having a size of
2N_(d-1).times.N_(d-1), a partition mode 996 having a size of
N_(d-1).times.2N_(d-1), and a partition mode 998 having a size of
N_(d-1).times.N_(d-1).
[0389] Prediction encoding may be repeatedly performed on one
partition having a size of 2N_(d-1).times.2N_(d-1), two partitions
having a size of 2N_(d-1).times.N_(d-1), two partitions having a
size of N_(d-1).times.2N_(d-1), four partitions having a size of
N_(d-1).times.N_(d-1) from among the partition modes to search for
a partition mode having a minimum encoding error.
[0390] Even when the partition mode 998 has the minimum encoding
error, since a maximum depth is d, a coding unit CU_(d-1) having a
depth of d-1 is no longer split to a lower depth, and a depth for
the coding units constituting a current largest coding unit 900 is
determined to be d-1 and a partition mode of the current largest
coding unit 900 may be determined to be N_(d-1).times.N_(d-1).
Also, since the maximum depth is d, split information for a coding
unit 952 having a depth of d-1 is not set.
[0391] A data unit 999 may be a `minimum unit` for the current
largest coding unit. A minimum unit according to an embodiment may
be a square data unit obtained by splitting a minimum coding unit
having a lowermost depth by 4. By performing the encoding
repeatedly, the video encoding apparatus 100 according to an
embodiment may select a depth having the minimum encoding error by
comparing encoding errors according to depths of the coding unit
900 to determine a depth, and set a corresponding partition mode
and a prediction mode as an encoding mode of the depth.
[0392] As such, the minimum encoding errors according to depths are
compared in all of the depths of 0, 1, . . . , d-1, d, and a depth
having the minimum encoding error may be determined as a depth. The
depth, the partition mode of the prediction unit, and the
prediction mode may be encoded and transmitted as split
information. Also, since a coding unit is split from a depth of 0
to a depth, only split information of the depth is set to 0, and
split information of depths excluding the depth is set to 1.
[0393] The image data and encoding information extractor 220 of the
video decoding apparatus 200 according to an embodiment may extract
and use the information about the depth and the prediction unit of
the coding unit 900 to decode the partition 912. The video decoding
apparatus 200 according to an embodiment may determine a depth, in
which split information is 0, as a depth by using split information
according to depths, and use split information of the corresponding
depth for decoding.
[0394] FIGS. 17, 18, and 19 are diagrams for describing a
relationship between coding units, prediction units, and
transformation units, according to various embodiments.
[0395] Coding units 1010 are coding units having a tree structure,
according to depths determined by the video encoding apparatus 100
according to an embodiment, in a largest coding unit. Prediction
units 1060 are partitions of prediction units of each of coding
units according to depths, and transformation units 1070 are
transformation units of each of coding units according to
depths.
[0396] When a depth of a largest coding unit is 0 in the coding
units 1010, depths of coding units 1012 and 1054 are 1, depths of
coding units 1014, 1016, 1018, 1028, 1050, and 1052 are 2, depths
of coding units 1020, 1022, 1024, 1026, 1030, 1032, and 1048 are 3,
and depths of coding units 1040, 1042, 1044, and 1046 are 4.
[0397] In the prediction units 1060, some encoding units 1014,
1016, 1022, 1032, 1048, 1050, 1052, and 1054 are obtained by
splitting the coding units in the encoding units 1010. That is,
partition modes in the coding units 1014, 1022, 1050, and 1054 have
a size of 2N.times.N, partition modes in the coding units 1016,
1048, and 1052 have a size of N.times.2N, and a partition modes of
the coding unit 1032 has a size of N.times.N. Prediction units and
partitions of the coding units 1010 are smaller than or equal to
each coding unit.
[0398] Transformation or inverse transformation is performed on
image data of the coding unit 1052 in the transformation units 1070
in a data unit that is smaller than the coding unit 1052. Also, the
coding units 1014, 1016, 1022, 1032, 1048, 1050, and 1052 in the
transformation units 1070 are data units different from those in
the prediction units 1060 in terms of sizes and shapes. That is,
the video encoding and decoding apparatuses 100 and 200 according
to embodiments may perform intra prediction, motion estimation,
motion compensation, transformation, and inverse transformation on
an individual data unit in the same coding unit.
[0399] Accordingly, encoding is recursively performed on each of
coding units having a hierarchical structure in each region of a
largest coding unit to determine an optimum coding unit, and thus
coding units having a recursive tree structure may be obtained.
Encoding information may include split information about a coding
unit, information about a partition mode, information about a
prediction mode, and information about a size of a transformation
unit. Table 1 shows the encoding information that may be set by the
video encoding and decoding apparatuses 100 and 200 according to
embodiments.
TABLE-US-00001 TABLE 1 Split Information 0 (Encoding on Coding Unit
having Size of 2N .times. 2N and Current Depth of d) Size of
Transformation Unit Split Partition Mode Information 0 Split
Information Symmetrical Asymmetrical of 1 of Prediction Partition
Partition Transformation Transformation Split Mode Type Type Unit
Unit Information 1 Intra 2N .times. 2N 2N .times. nU 2N .times. 2N
N .times. N Repeatedly Inter 2N .times. N 2N .times. nD
(Symmetrical Encode Skip N .times. 2N nL .times. 2N Partition Mode)
Coding (Only N .times. N nR .times. 2N N/2 .times. N/2 etc. Units
having 2N .times. 2N) (Asymmetrical Lower Depth Partition Mode) of
d + 1
[0400] The output unit 130 of the video encoding apparatus 100
according to an embodiment may output the encoding information
about the coding units having a tree structure, and the image data
and encoding information extractor 220 of the video decoding
apparatus 200 according to an embodiment may extract the encoding
information about the coding units having a tree structure from a
received bitstream.
[0401] Split information indicates whether a current coding unit is
split into coding units of a lower depth. If split information of a
current depth d is 0, a depth, in which a current coding unit is no
longer split into a lower depth, is a depth, and thus information
about a partition mode, prediction mode, and a size of a
transformation unit may be defined for the depth. If the current
coding unit is further split according to the split information,
encoding has to be independently performed on four split coding
units of a lower depth.
[0402] A prediction mode may be one of an intra mode, an inter
mode, and a skip mode. The intra mode and the inter mode may be
defined in all partition modes, and the skip mode may be defined
only in a partition mode having a size of 2N.times.2N.
[0403] The information about the partition mode may indicate
symmetrical partition modes having sizes of 2N.times.2N,
2N.times.N, N.times.2N, and N.times.N, which are obtained by
symmetrically splitting a height or a width of a prediction unit,
and asymmetrical partition modes having sizes of 2N.times.nU,
2N.times.nD, nL.times.2N, and nR.times.2N, which are obtained by
asymmetrically splitting the height or width of the prediction
unit. The asymmetrical partition modes having the sizes of
2N.times.nU and 2N.times.nD may be respectively obtained by
splitting the height of the prediction unit in 1:3 and 3:1, and the
asymmetrical partition modes having the sizes of nL.times.2N and
nR.times.2N may be respectively obtained by splitting the width of
the prediction unit in 1:3 and 3:1.
[0404] The size of the transformation unit may be set to be two
types in the intra mode and two types in the inter mode. That is,
if split information of the transformation unit is 0, the size of
the transformation unit may be 2N.times.2N, which is the size of
the current coding unit. If the split information of the
transformation unit is 1, the transformation units may be obtained
by splitting the current coding unit. Also, if a partition mode of
the current coding unit having the size of 2N.times.2N is a
symmetrical partition mode, a size of a transformation unit may be
N.times.N, and if the partition type of the current coding unit is
an asymmetrical partition mode, the size of the transformation unit
may be N/2.times.N/2.
[0405] The encoding information about coding units having a tree
structure according to an embodiment may be assigned to at least
one of a coding unit corresponding to a depth, a prediction unit,
and a minimum unit. The coding unit corresponding to the depth may
include at least one of a prediction unit and a minimum unit that
have the same encoding information.
[0406] Accordingly, it is determined whether adjacent data units
are included in the same coding unit corresponding to the depth by
comparing a plurality of pieces of encoding information of the
adjacent data units. Also, a corresponding coding unit
corresponding to a depth is determined by using encoding
information of a data unit, and thus a distribution of depths in a
largest coding unit may be determined.
[0407] Accordingly, if a current coding unit is predicted based on
encoding information of adjacent data units, encoding information
of data units in deeper coding units adjacent to the current coding
unit may be directly referred to and used.
[0408] As another example, if a current coding unit is
prediction-encoded by referring to adjacent coding units, a data
unit that is adjacent to the current coding unit and is in adjacent
deeper coding units is searched by using a plurality of pieces of
encoding information of the adjacent coding units, in such a manner
that the adjacent coding units may be referred to.
[0409] FIG. 20 is a diagram for describing a relationship between a
coding unit, a prediction unit, and a transformation unit,
according to encoding mode information of Table 1.
[0410] A largest coding unit 1300 includes coding units 1302, 1304,
1306, 1312, 1314, 1316, and 1318 of depths. Here, since the coding
unit 1318 is a coding unit of a depth, split information may be set
to 0. Information about a partition mode of the coding unit 1318
having a size of 2N.times.2N may be set to be one of a partition
mode 1322 having a size of 2N.times.2N, a partition mode 1324
having a size of 2N.times.N, a partition mode 1326 having a size of
N.times.2N, a partition mode 1328 having a size of N.times.N, a
partition mode 1332 having a size of 2N.times.nU, a partition mode
1334 having a size of 2N.times.nD, a partition mode 1336 having a
size of nL.times.2N, and a partition mode 1338 having a size of
nR.times.2N.
[0411] Split information (TU size flag) of a transformation unit is
a type of a transformation index. A size of the transformation unit
corresponding to the transformation index may be changed according
to a prediction unit type or a partition mode of the coding
unit.
[0412] For example, when information about the partition mode is
set to be symmetrical, i.e. the partition mode 1322 having a size
of 2N.times.2N, the partition mode 1324 having a size of
2N.times.N, the partition mode 1326 having a size of N.times.2N, or
the partition mode 1328 having a size of N.times.N, a
transformation unit 1342 having a size of 2N.times.2N may be set if
the TU size flag of the transformation unit is 0, and a
transformation unit 1344 having a size of N.times.N may be set if
the TU size flag is 1.
[0413] When the information about the partition mode is set to be
asymmetrical, i.e., the partition mode 1332 having a size of
2N.times.nU, the partition mode 1334 having a size of 2N.times.nD,
the partition mode 1336 having a size of nL.times.2N, or the
partition mode 1338 having a size of nR.times.2N, a transformation
unit 1352 having a size of 2N.times.2N may be set if the TU size
flag is 0, and a transformation unit 1354 having a size of
N/2.times.N/2 may be set if the TU size flag is 1.
[0414] Referring to FIG. 19, the TU size flag is a flag having a
value or 0 or 1, but the TU size flag according to an embodiment is
not limited to a flag of 1 bit, and the transformation unit may be
hierarchically split while the TU size flag increases from 0. The
TU size flag may be an example of the transformation index.
[0415] In this case, the size of the transformation unit that has
been actually used may be expressed by using the TU size flag
according to an embodiment together with a maximum size of the
transformation unit and a minimum size of the transformation unit.
The video encoding apparatus 100 according to an embodiment may
encode maximum transformation unit size information, minimum
transformation unit size information, and maximum TU size flag
information. The result of encoding the maximum transformation unit
size information, the minimum transformation unit size information,
and the maximum TU size flag information may be inserted into an
SPS. The video decoding apparatus 200 according to an embodiment
may decode video by using the maximum transformation unit size
information, the minimum transformation unit size information, and
the maximum TU size flag information.
[0416] For example, (a) if a size of a current coding unit is
64.times.64 and a maximum transformation unit size is 32.times.32,
(a-1) then a size of a transformation unit may be 32.times.32 when
a TU size flag is 0, (a-2) may be 16.times.16 when the TU size flag
is 1, and (a-3) may be 8.times.8 when the TU size flag is 2.
[0417] As another example, (b) if the size of the current coding
unit is 32.times.32 and a minimum transformation unit size is
32.times.32, (b-1) then the size of the transformation unit may be
32.times.32 when the TU size flag is 0. Here, the TU size flag
cannot be set to a value other than 0, since the size of the
transformation unit cannot be less than 32.times.32.
[0418] As another example, (c) if the size of the current coding
unit is 64.times.64 and the maximum TU size flag is 1, then the TU
size flag may be 0 or 1. Here, the TU size flag cannot be set to a
value other than 0 or 1.
[0419] Thus, if it is defined that the maximum TU size flag is
`MaxTransformSizeIndex`, a minimum transformation unit size is
`MinTransformSize`, and a transformation unit size is `RootTuSize`
when the TU size flag is 0, then a current minimum transformation
unit size `CurrMinTuSize` that can be determined in a current
coding unit, may be defined by Equation (1):
CurrMinTuSize=max(MinTransformSize, RootTuSize/(2
MaxTransformSizeIndex)) (1)
[0420] Compared to the current minimum transformation unit size
`CurrMinTuSize` that can be determined in the current coding unit,
a transformation unit size `RootTuSize` when the TU size flag is 0
may denote a maximum transformation unit size that can be selected
in the system. In Equation (1), `RootTuSize/(2
MaxTransformSizeIndex)` denotes a transformation unit size when the
transformation unit size `RootTuSize`, when the TU size flag is 0,
is split a number of times corresponding to the maximum TU size
flag, and `MinTransformSize` denotes a minimum transformation size.
Thus, a smaller value from among `RootTuSize/(2
MaxTransformSizeIndex)` and `MinTransformSize` may be the current
minimum transformation unit size `CurrMinTuSize` that can be
determined in the current coding unit.
[0421] The maximum transformation unit size RootTuSize according to
an embodiment may vary according to a prediction mode.
[0422] For example, if a current prediction mode is an inter mode,
then `RootTuSize` may be determined by using Equation (2) below. In
Equation (2), `MaxTransformSize` denotes a maximum transformation
unit size, and `PUSize` denotes a current prediction unit size.
RootTuSize=min(MaxTransformSize, PUSize) (2)
[0423] That is, if the current prediction mode is the inter mode,
the transformation unit size `RootTuSize`, when the TU size flag is
0, may be a smaller value from among the maximum transformation
unit size and the current prediction unit size.
[0424] If a prediction mode of a current partition unit is an intra
mode, `RootTuSize` may be determined by using Equation (3) below.
In Equation (3), `PartitionSize` denotes the size of the current
partition unit.
RootTuSize=min(MaxTransformSize, PartitionSize) (3)
[0425] That is, if the current prediction mode is the intra mode,
the transformation unit size `RootTuSize` when the TU size flag is
0 may be a smaller value from among the maximum transformation unit
size and the size of the current partition unit.
[0426] However, the current maximum transformation unit size
`RootTuSize` that varies according to the type of a prediction mode
in a partition unit is just an example and the present disclosure
is not limited thereto.
[0427] According to the video encoding method based on coding units
having a tree structure as described with reference to FIGS. 8
through 20, image data of a spatial domain is encoded for each
coding unit of a tree structure. According to the video decoding
method based on coding units having a tree structure, decoding is
performed for each largest coding unit to reconstruct image data of
a spatial domain. Thus, a picture and a video that is a picture
sequence may be reconstructed. The reconstructed video may be
reproduced by a reproducing apparatus, may be stored in a storage
medium, or may be transmitted through a network.
[0428] The embodiments according to the present disclosure may be
written as computer programs and may be implemented in general-use
digital computers that execute the programs using a
computer-readable recording medium. Examples of the
computer-readable recording medium include magnetic storage media
(e.g., ROM, floppy discs, hard discs, etc.) and optical recording
media (e.g., CD-ROMs, or DVDs).
[0429] For convenience of description, the inter-layer video
encoding method and/or the video encoding method described above
with reference to FIGS. 1A through 20 will be collectively referred
to as a `video encoding method of the present disclosure`. In
addition, the inter-layer video decoding method and/or the video
decoding method described above with reference to FIGS. 1A through
20 will be referred to as a `video decoding method of the present
disclosure`.
[0430] Also, a video encoding apparatus including the inter-layer
video encoding apparatus 10, the video encoding apparatus 100, or
the image encoder 400, which has been described with reference to
FIGS. 1A through 20, will be referred to as a `video encoding
apparatus of the present disclosure`. In addition, a video decoding
apparatus including the inter-layer video decoding apparatus 20,
the video decoding apparatus 200, or the image decoder 500, which
has been described with reference to FIGS. 1 A through 20, will be
referred to as a `video decoding apparatus of the present
disclosure`.
[0431] The computer-readable recording medium such as a disc 26000
that stores the programs according to an embodiment will now be
described in detail.
[0432] FIG. 21 is a diagram of a physical structure of the disc
26000 in which a program is stored, according to various
embodiments. The disc 26000, which is a storage medium, may be a
hard drive, a compact disc-read only memory (CD-ROM) disc, a
Blu-ray disc, or a digital versatile disc (DVD). The disc 26000
includes a plurality of concentric tracks Tr that are each divided
into a specific number of sectors Se in a circumferential direction
of the disc 26000. In a specific region of the disc 26000 according
to an embodiment, a program that executes the quantization
parameter determining method, the video encoding method, and the
video decoding method described above may be assigned and
stored.
[0433] A computer system embodied using the storage medium that
stores the program for executing the video encoding method and the
video decoding method as described above will now be described with
reference to FIG. 22.
[0434] FIG. 22 is a diagram of a disc drive 26800 for recording and
reading a program by using the disc 26000. A computer system 27000
may store a program that executes at least one of a video encoding
method and a video decoding method of the present disclosure, in
the disc 26000 via the disc drive 26800. In order to run the
program stored in the disc 26000 in the computer system 27000, the
program may be read from the disc 26000 and be transmitted to the
computer system 26700 by using the disc drive 27000.
[0435] The program that executes at least one of a video encoding
method and a video decoding method of the present disclosure may be
stored not only in the disc 26000 illustrated in FIGS. 21 and 22
but also in a memory card, a ROM cassette, or a solid state drive
(SSD).
[0436] A system to which the video encoding method and the video
decoding method according to the embodiments described above are
applied will be described below.
[0437] FIG. 23 is a diagram of an overall structure of a content
supply system 11000 for providing a content distribution service. A
service area of a communication system is divided into
predetermined-sized cells, and wireless base stations 11700, 11800,
11900, and 12000 are installed in these cells, respectively.
[0438] The content supply system 11000 includes a plurality of
independent devices. For example, the plurality of independent
devices, such as a computer 12100, a personal digital assistant
(PDA) 12200, a video camera 12300, and a mobile phone 12500, are
connected to the Internet 11100 via an internet service provider
11200, a communication network 11400, and the wireless base
stations 11700, 11800, 11900, and 12000.
[0439] However, the content supply system 11000 is not limited to
as illustrated in FIG. 24, and devices may be selectively connected
thereto. The plurality of independent devices may be directly
connected to the communication network 11400, not via the wireless
base stations 11700, 11800, 11900, and 12000.
[0440] The video camera 12300 is an imaging device, e.g., a digital
video camera, which is capable of capturing video images. The
mobile phone 12500 may employ at least one communication method
from among various protocols, e.g., Personal Digital Communications
(PDC), Code Division Multiple Access (CDMA), Wideband-Code Division
Multiple Access (W-CDMA), Global System for Mobile Communications
(GSM), and Personal Handyphone System (PHS).
[0441] The video camera 12300 may be connected to a streaming
server 11300 via the wireless base station 11900 and the
communication network 11400. The streaming server 11300 allows
content received from a user via the video camera 12300 to be
streamed via a real-time broadcast. The content received from the
video camera 12300 may be encoded by the video camera 12300 or the
streaming server 11300. Video data captured by the video camera
12300 may be transmitted to the streaming server 11300 via the
computer 12100.
[0442] Video data captured by a camera 12600 may also be
transmitted to the streaming server 11300 via the computer 12100.
The camera 12600 is an imaging device capable of capturing both
still images and video images, similar to a digital camera. The
video data captured by the camera 12600 may be encoded using the
camera 12600 or the computer 12100. Software that performs encoding
and decoding video may be stored in a computer-readable recording
medium, e.g., a CD-ROM disc, a floppy disc, a hard disc drive, an
SSD, or a memory card, which may be accessible by the computer
12100.
[0443] If video data is captured by a camera built in the mobile
phone 12500, the video data may be received from the mobile phone
12500.
[0444] The video data may also be encoded by a large scale
integrated circuit (LSI) system installed in the video camera
12300, the mobile phone 12500, or the camera 12600.
[0445] In the content supply system 11000 according to an
embodiment, content data, e.g., content recorded during a concert,
which has been recorded by a user using the video camera 12300, the
camera 12600, the mobile phone 12500, or another imaging device is
encoded and is transmitted to the streaming server 11300. The
streaming server 11300 may transmit the encoded content data in a
type of a streaming content to other clients that request the
content data.
[0446] The clients are devices capable of decoding the encoded
content data, e.g., the computer 12100, the PDA 12200, the video
camera 12300, or the mobile phone 12500. Thus, the content supply
system 11000 allows the clients to receive and reproduce the
encoded content data. Also, the content supply system 11000 allows
the clients to receive the encoded content data and decode and
reproduce the encoded content data in real-time, thereby enabling
personal broadcasting.
[0447] The video encoding apparatus and the video decoding
apparatus of the present disclosure may be applied to encoding and
decoding operations of the plurality of independent devices
included in the content supply system 11000.
[0448] With reference to FIGS. 24 and 25, an embodiment of the
mobile phone 12500 included in the content supply system 11000 will
now be described in detail.
[0449] FIG. 24 illustrates an external structure of the mobile
phone 12500 to which the video encoding method and the video
decoding method of the present disclosure are applied, according to
various embodiments. The mobile phone 12500 may be a smart phone,
the functions of which are not limited and a large number of the
functions of which may be changed or expanded.
[0450] The mobile phone 12500 includes an internal antenna 12510
via which a radio-frequency (RF) signal may be exchanged with the
wireless base station 12000 of FIG. 21, and includes a display
screen 12520 for displaying images captured by a camera 12530 or
images that are received via the antenna 12510 and decoded, e.g., a
liquid crystal display (LCD) or an organic light-emitting diode
(OLED) screen. The mobile phone 12500 includes an operation panel
12540 including a control button and a touch panel. If the display
screen 12520 is a touch screen, the operation panel 12540 further
includes a touch sensing panel of the display screen 12520. The
mobile phone 12500 includes a speaker 12580 for outputting voice
and sound or another type of sound output unit, and a microphone
12550 for inputting voice and sound or another type sound input
unit. The mobile phone 12500 further includes the camera 12530,
such as a charge-coupled device (CCD) camera, to capture video and
still images. The mobile phone 12500 may further include a storage
medium 12570 for storing encoded/decoded data, e.g., video or still
images captured by the camera 12530, received via email, or
obtained according to various ways; and a slot 12560 via which the
storage medium 12570 is loaded into the mobile phone 12500. The
storage medium 12570 may be a flash memory, e.g., a secure digital
(SD) card or an electrically erasable and programmable read only
memory (EEPROM) included in a plastic case.
[0451] FIG. 25 illustrates an internal structure of the mobile
phone 12500. In order to systemically control parts of the mobile
phone 12500 including the display screen 12520 and the operation
panel 12540, a power supply circuit 12700, an operation input
controller 12640, an image encoding unit 12720, a camera interface
12630, an LCD controller 12620, an image decoding unit 12690, a
multiplexer/demultiplexer 12680, a recording/reading unit 12670, a
modulation/demodulation unit 12660, and a sound processor 12650 are
connected to a central controller 12710 via a synchronization bus
12730.
[0452] If a user operates a power button and sets from a `power
off` state to a `power on` state, the power supply circuit 12700
supplies power to all the parts of the mobile phone 12500 from a
battery pack, thereby setting the mobile phone 12500 in an
operation mode.
[0453] The central controller 12710 includes a central processing
unit (CPU), a ROM, and a RAM.
[0454] While the mobile phone 12500 transmits communication data to
the outside, a digital signal is generated by the mobile phone
12500 under control of the central controller 12710. For example,
the sound processor 12650 may generate a digital sound signal, the
image encoding unit 12720 may generate a digital image signal, and
text data of a message may be generated via the operation panel
12540 and the operation input controller 12640. When a digital
signal is transmitted to the modulation/demodulation unit 12660
under control of the central controller 12710, the
modulation/demodulation unit 12660 modulates a frequency band of
the digital signal, and a communication circuit 12610 performs
digital-to-analog conversion (DAC) and frequency conversion on the
frequency band-modulated digital sound signal. A transmission
signal output from the communication circuit 12610 may be
transmitted to a voice communication base station or the wireless
base station 12000 via the antenna 12510.
[0455] For example, when the mobile phone 12500 is in a
conversation mode, a sound signal obtained via the microphone 12550
is converted into a digital sound signal by the sound processor
12650, under control of the central controller 12710. The digital
sound signal may be converted into a transmission signal via the
modulation/demodulation unit 12660 and the communication circuit
12610, and may be transmitted via the antenna 12510.
[0456] When a text message, e.g., email, is transmitted in a data
communication mode, text data of the text message is input via the
operation panel 12540 and is transmitted to the central controller
12610 via the operation input controller 12640. Under control of
the central controller 12610, the text data is transformed into a
transmission signal via the modulation/demodulation unit 12660 and
the communication circuit 12610 and is transmitted to the wireless
base station 12000 via the antenna 12510.
[0457] In order to transmit image data in the data communication
mode, image data captured by the camera 12530 is provided to the
image encoding unit 12720 via the camera interface 12630. The
captured image data may be directly displayed on the display screen
12520 via the camera interface 12630 and the LCD controller
12620.
[0458] A structure of the image encoding unit 12720 may correspond
to that of the video encoding apparatus 100 described above. The
image encoding unit 12720 may transform the image data received
from the camera 12530 into compressed and encoded image data
according to the video encoding method described above, and then
output the encoded image data to the multiplexer/demultiplexer
12680. During a recording operation of the camera 12530, a sound
signal obtained by the microphone 12550 of the mobile phone 12500
may be transformed into digital sound data via the sound processor
12650, and the digital sound data may be transmitted to the
multiplexer/demultiplexer 12680.
[0459] The multiplexer/demultiplexer 12680 multiplexes the encoded
image data received from the image encoding unit 12720, together
with the sound data received from the sound processor 12650. A
result of multiplexing the data may be transformed into a
transmission signal via the modulation/demodulation unit 12660 and
the communication circuit 12610, and may then be transmitted via
the antenna 12510.
[0460] While the mobile phone 12500 receives communication data
from an outer source, frequency recovery and analog-to-digital
conversion (ADC) are performed on a signal received via the antenna
12510 to transform the signal into a digital signal. The
modulation/demodulation unit 12660 modulates a frequency band of
the digital signal. The frequency-band modulated digital signal is
transmitted to the video decoding unit 12690, the sound processor
12650, or the LCD controller 12620, according to the type of the
digital signal.
[0461] In the conversation mode, the mobile phone 12500 amplifies a
signal received via the antenna 12510, and obtains a digital sound
signal by performing frequency conversion and ADC on the amplified
signal. A received digital sound signal is transformed into an
analog sound signal via the modulation/demodulation unit 12660 and
the sound processor 12650, and the analog sound signal is output
via the speaker 12580, under control of the central controller
12710.
[0462] When in the data communication mode, data of a video file
accessed at an Internet website is received, a signal received from
the wireless base station 12000 via the antenna 12510 is output as
multiplexed data via the modulation/demodulation unit 12660, and
the multiplexed data is transmitted to the
multiplexer/demultiplexer 12680.
[0463] In order to decode the multiplexed data received via the
antenna 12510, the multiplexer/demultiplexer 12680 demultiplexes
the multiplexed data into an encoded video data stream and an
encoded audio data stream. Via the synchronization bus 12730, the
encoded video data stream and the encoded audio data stream are
provided to the video decoding unit 12690 and the sound processor
12650, respectively.
[0464] A structure of the image decoding unit 12690 may correspond
to that of the video decoding apparatus 200 described above. The
image decoding unit 12690 may decode the encoded video data to
obtain reconstructed video data and provide the reconstructed video
data to the display screen 12520 via the LCD controller 12620,
according to a video decoding method employed by the video decoding
apparatus 200 or the image decoder 500 described above.
[0465] Thus, the data of the video file accessed at the Internet
website may be displayed on the display screen 12520. At the same
time, the sound processor 12650 may transform audio data into an
analog sound signal, and provide the analog sound signal to the
speaker 12580. Thus, audio data contained in the video file
accessed at the Internet website may also be reproduced via the
speaker 12580.
[0466] The mobile phone 12500 or another type of communication
terminal may be a transceiving terminal including both a video
encoding apparatus and a video decoding apparatus of the present
disclosure, may be a transceiving terminal including only the video
encoding apparatus, or may be a transceiving terminal including
only the video decoding apparatus.
[0467] A communication system according to the present disclosure
is not limited to the communication system described above with
reference to FIG. 24. For example, FIG. 26 illustrates a digital
broadcasting system employing a communication system, according to
various embodiments. The digital broadcasting system of FIG. 26
according to an embodiment may receive a digital broadcast
transmitted via a satellite or a terrestrial network by using the
video encoding apparatus and the video decoding apparatus of the
present disclosure.
[0468] In more detail, a broadcasting station 12890 transmits a
video data stream to a communication satellite or a broadcasting
satellite 12900 by using radio waves. The broadcasting satellite
12900 transmits a broadcast signal, and the broadcast signal is
transmitted to a satellite broadcast receiver via a household
antenna 12860. In every house, an encoded video stream may be
decoded and reproduced by a TV receiver 12810, a set-top box 12870,
or another device.
[0469] When the video decoding apparatus of the present disclosure
is implemented in a reproducing apparatus 12830, the reproducing
apparatus 12830 may parse and decode an encoded video stream
recorded on a storage medium 12820, such as a disc or a memory card
to reconstruct digital signals. Thus, the reconstructed video
signal may be reproduced, for example, on a monitor 12840.
[0470] In the set-top box 12870 connected to the antenna 12860 for
a satellite/terrestrial broadcast or a cable antenna 12850 for
receiving a cable television (TV) broadcast, a video decoding
apparatus of the present disclosure may be installed. Data output
from the set-top box 12870 may also be reproduced on a TV monitor
12880.
[0471] As another example, a video decoding apparatus of the
present disclosure may be installed in the TV receiver 12810
instead of the set-top box 12870.
[0472] An automobile 12920 that has an appropriate antenna 12910
may receive a signal transmitted from the satellite 12900 or the
wireless base station 11700 of FIG. 23. A decoded video may be
reproduced on a display screen of an automobile navigation system
12930 installed in the automobile 12920.
[0473] A video signal may be encoded by a video encoding apparatus
of the present disclosure and may then be recorded to and stored in
a storage medium. Specifically, an image signal may be stored in a
DVD disc 12960 by a DVD recorder or may be stored in a hard disc by
a hard disc recorder 12950. As another example, the video signal
may be stored in an SD card 12970. If the hard disc recorder 12950
includes a video decoding apparatus of the present disclosure
according to an embodiment, a video signal recorded on the DVD disc
12960, the SD card 12970, or another storage medium may be
reproduced on the TV monitor 12880.
[0474] The automobile navigation system 12930 may not include the
camera 12530, the camera interface 12630, and the image encoding
unit 12720 of FIG. 26. For example, the computer 12100 and the TV
receiver 12810 may not include the camera 12530, the camera
interface 12630, and the image encoding unit 12720 of FIG. 26.
[0475] FIG. 27 is a diagram illustrating a network structure of a
cloud computing system using a video encoding apparatus and a video
decoding apparatus, according to various embodiments.
[0476] The cloud computing system of the present disclosure may
include a cloud computing server 14000, a user database (DB) 14100,
a plurality of computing resources 14200, and a user terminal.
[0477] The cloud computing system provides an on-demand outsourcing
service of the plurality of computing resources 14200 via a data
communication network, e.g., the Internet, in response to a request
from the user terminal. Under a cloud computing environment, a
service provider provides users with desired services by combining
computing resources at data centers located at physically different
locations by using virtualization technology. A service user does
not have to install computing resources, e.g., an application, a
storage, an operating system (OS), and security, into his/her own
terminal in order to use them, but may select and use desired
services from among services in a virtual space generated through
the virtualization technology, at a desired point in time.
[0478] A user terminal of a specified service user is connected to
the cloud computing server 14000 via a data communication network
including the Internet and a mobile telecommunication network. User
terminals may be provided cloud computing services, and
particularly video reproduction services, from the cloud computing
server 14000. The user terminals may be various types of electronic
devices capable of being connected to the Internet, e.g., a desktop
PC 14300, a smart TV 14400, a smart phone 14500, a notebook
computer 14600, a portable multimedia player (PMP) 14700, a tablet
PC 14800, and the like.
[0479] The cloud computing server 14000 may combine the plurality
of computing resources 14200 distributed in a cloud network and
provide user terminals with a result of combining. The plurality of
computing resources 14200 may include various data services, and
may include data uploaded from user terminals. As described above,
the cloud computing server 14000 may provide user terminals with
desired services by combining video database distributed in
different regions according to the virtualization technology.
[0480] User information about users who have subscribed for a cloud
computing service is stored in the user DB 14100. The user
information may include logging information, addresses, names, and
personal credit information of the users. The user information may
further include indexes of videos. Here, the indexes may include a
list of videos that have already been reproduced, a list of videos
that are being reproduced, a pausing point of a video that was
being reproduced, and the like.
[0481] Information about a video stored in the user DB 14100 may be
shared between user devices. For example, when a video service is
provided to the notebook computer 14600 in response to a request
from the notebook computer 14600, a reproduction history of the
video service is stored in the user DB 14100. When a request to
reproduce this video service is received from the smart phone
14500, the cloud computing server 14000 searches for and reproduces
this video service, based on the user DB 14100. When the smart
phone 14500 receives a video data stream from the cloud computing
server 14000, a process of reproducing video by decoding the video
data stream is similar to an operation of the mobile phone 12500
described above with reference to FIG. 24.
[0482] The cloud computing server 14000 may refer to a reproduction
history of a desired video service, stored in the user DB 14100.
For example, the cloud computing server 14000 receives a request to
reproduce a video stored in the user DB 14100, from a user
terminal. If this video was being reproduced, then a method of
streaming this video, performed by the cloud computing server
14000, may vary according to the request from the user terminal,
i.e., according to whether the video will be reproduced, starting
from a start thereof or a pausing point thereof. For example, if
the user terminal requests to reproduce the video, starting from
the start thereof, the cloud computing server 14000 transmits
streaming data of the video starting from a first frame thereof to
the user terminal. If the user terminal requests to reproduce the
video, starting from the pausing point thereof, the cloud computing
server 14000 transmits streaming data of the video starting from a
frame corresponding to the pausing point, to the user terminal.
[0483] In this case, the user terminal may include a video decoding
apparatus of the present disclosure as described above with
reference to FIGS. 1A through 20. As another example, the user
terminal may include a video encoding apparatus of the present
disclosure as described above with reference to FIGS. 1A through
20. Alternatively, the user terminal may include both the video
decoding apparatus and the video encoding apparatus of the present
disclosure as described above with reference to FIGS. 1A through
20.
[0484] Various applications of a video encoding method, a video
decoding method, a video encoding apparatus, and a video decoding
apparatus according to various embodiments described above with
reference to FIGS. 1A through 20 have been described above with
reference to FIGS. 21 through 27. However, methods of storing the
video encoding method and the video decoding method in a storage
medium or methods of implementing the video encoding apparatus and
the video decoding apparatus in a device, according to various
embodiments, are not limited to the embodiments described above
with reference to FIGS. 21 through 27.
[0485] It will be understood by one of ordinary skill in the art
that various changes in form and details may be made therein
without departing from the spirit and scope of the disclosure as
defined by the appended claims. The embodiments should be
considered in a descriptive sense only and not for purposes of
limitation. Therefore, the scope of the disclosure is defined not
by the detailed description of the disclosure but by the appended
claims, and all differences within the scope will be construed as
being included in the present disclosure.
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